Gaseous Combustion Products Research Articles

Research of Mechanism of Fire Protection with Wood Lacquer

The results of researches of wood burning parameters and influence of fire-retardant substances on them are given. Studies have shown that the process of heat insulation of a wooden structure is the formation of soot-like products on the surface of natural combustible material. Under the action of the burner flame on the protected sample treated with impregnating solutions based on a mixture of ammonium phosphate with antiseptic, the temperature of gaseous combustion products was 230 oC, and weight loss did not exceed 9%, while wood treated with a composition of urea and phosphoric acids and starch showed temperature of 160 oС with a weight loss of 3.6%. It is established that fire protection by coatings provides a low rate of burnout of wood samples and with increasing temperature exposure and translates into a non-flammable material that does not spread the flame on the surface.

Composition of solid and gaseous primary combustion products of boron-based fuel-rich propellant

The investigation of the primary combustion products of boron-based fuel-rich propellants is conducive to understanding the mechanism of the two-stage combustion process and provides important information for the prediction and organization of secondary combustion processes. The present investigation methods include numerical simulation and experimental analysis. The former deviates considerably from the actual conditions. The latter is currently a reliable and practical method, although it is difficult to quantify when the components are complex. In this work, SEM, LPSA, XRD, XPS, IC, ICP–MS, AAS, EDS, and chemical analysis methods were employed to qualitatively and quantitatively analyze the 3 solid products (aggregations, condensed-phase products, and flocculent products) at 1, 5, and 10 bar. GC, GC–MS, and IC combined with chemical tests were adopted to investigate the gaseous products (including chlorine-containing gas) for the first time. The solid products primarily included B2O3, B(HO)3, unburned boron, KB5O8(H2O)4, KCl, C, NH4Cl, NH4Mg(H2O)6Cl3, B13C2, Fe3O4, Mo, MgO, Mg(OH)2, MoO3, C3N4, BN, MgCO3(H2O)3 (or MgCO3), MoO2, Fe4(Fe(CN)6)3, and FeB (or BFe4), and the first 7 were dominant. The reaction degree of boron was less than 50 wt% (increasing with increasing pressure), indicating the significance of the secondary combustion process. The reacted boron was likely to react with O and C but not with N. The generated B2O3 vapor easily combined with H2O to form B(HO)3 or reacted with KCl (from the thermal decomposition of KP) and H2O to produce KB5O8(H2O)4 after cooling. There was less B13C2 (its content increased with increasing pressure, resulting in increases in particle size), since it was easily oxidized to generate B2O3. NH4Cl was produced by the oxidation-reduction reaction between the NH3 and HClO4 released from large-sized AP, and some of it crystallized with MgCl2 and H2O to form NH4Mg(H2O)6Cl3. The gaseous products primarily included N2, H2, CO, CH4, CO2, C2H4, C2H2, HCl, C4H6, C3H6, Cl2, C6H6, and other hydrocarbons. N2 and H2 had the highest content. The N2 content increased with increasing pressure, while the content of the combustible gases decreased, indicating that high pressure promotes the propellant reaction. The results also show that high pressure was conducive to the low-temperature decomposition of AP (producing more HCl and Cl2) and the reaction of boron and hydrocarbons (generating more B13C2), while it had an adverse effect on the C reaction (producing less COx and mostly CO). Nevertheless, the increasing pressure had little effect on the combustion product components but did affect the content within the pressure range.

Elaboration, thermogravimetric analysis, and fire testing of a new type of wood‐sawdust composite materials based on epoxy–amine polymers modified with copper(II) hexafluorosilicate

SUMMARYThe study reports the development of a new type of wood‐sawdust (WS) composite based on CuSiF6‐modified epoxy–amine polymers (EAPs) with reduced combustibility. The thermo‐oxidative behavior of the obtained WS/EAP–CuSiF6 and WS/EAP specimens was studied using the complex thermal analysis. Thermal analysis data show that incorporating CuSiF6 (flame retardant) into WS/EAP increases the thermal oxidation resistance of WS/EAP–CuSiF6. It is shown that for WS/EAP–CuSiF6 and WS/EAP, thermo‐oxidative destruction ends at 571°C and 625°C, and the maximum temperature of this exothermic process is 435°C and 499°C, respectively. The combustibility of WS/EAP–CuSiF6 and WS/EAP was studied by the “ceramic tube” (CT) method. The CT results obtained demonstrate impressive differences in the combustibility of these two composites; the maximum temperature of gaseous combustion products for WS/EAP–CuSiF6 is 265°C, and for WS/EAP, it is 910°C. Flammability tests for WS/EAP–CuSiF6 and WS/EAP were carried out in accordance with ASTM D635‐18 and ASTM D3801‐19a. According to the results of vertical burning tests, the WS/EAP–CuSiF6 composite material was classified as V‐0.

A conceptual framework for biomass gasifier design using a semi-empirical model and heuristic algorithm

Biomass gasification is a cost-effective process that converts biomass into clean and combustible gaseous products. Gasifier design plays an important role in the performance of biomass gasification. This study proposed a novel gasifier design method which used the thermodynamic artificial neural network (T-ANN) model to accurately predict gasification products, and the non-dominated sorting genetic algorithm-II to search for optimal gasifier design parameters. 166 reported experimental data were used to establish the T-ANN model and evaluate its performance. The results showed that the semi-empirical T-ANN model performed better prediction accuracy and robustness than traditional theoretical and empirical models. The optimal model showed an accuracy within 8.81 ± 1.21% at 95% confidence interval. The satisfying performance could be attributed to accurate prediction of gasification temperature and a comprehensive consideration of influential parameters. Among various input parameters, gasification temperature contributed the most (>15%) to the prediction accuracy. Applicability of the proposed design method was demonstrated in designing a 200 kW biomass gasifier. It was also found that this design method was promisingly superior for tasks with multiple design targets. The design results show that the lower heating value of syngas, syngas yield and cold gas efficiency were increased by 6.95%, 1.9% and 8.3%, respectively. Hopefully, this study could shed a light on the application of state-of-the-art models and algorithms in biomass gasifier design and promisingly enhance the development of biomass gasification industry.

Разработка экспресс-метода исследования токсичности продуктов горения современных кабельных пластикатов

In case of fire, combustible materials and products made on their basis have a decisive role in the development of combustion, formation and spread of foreground risks. Normative legal documents restrict the use of fire hazardous materials, but it is impossible to exclude their use completely. In case of fire, in addition to flame and high temperatures are formed smoke and toxic gaseous products of combustion. The basis of the most common products is polyvinyl chloride - one of the most common fire hazardous materials, whose production volumes have only increased in recent years. In the course of this work, an express method has been developed and tested for the qualitative and quantitative determination of toxic substances contained in combustion products of plastic compounds based on polyvinyl chloride.

Расчет теплоемкости продуктов сгорания компримированного газового топлива марок «А» и «Б» в дизелях

The article underlines the interest to using gas fuel in diesel engines of the coastal fishing vessels. If the change to liquefied natural gas is limited by the lack of bunkering capabilities in the Russian ports, using compressed gas has become widespread in transport and in the household. A number of gas fueling stations are already available for this purpose. It seems reasonable to start the conversion of the port fleet to compressed gas from using the motor gas bottling equipment for that purpose. It is important to evaluate the change in engine performance parameters when converting to compressed gas. Compressed gas is a mixture of gases such as propane, ethane, butane, methane, etc. There is given the percentage of each gas content, according to GOST. The quantitative composition of the pure compressed gas combustion outcomes, as well as the gas ignited by the ignition diesel fuel was determined by the oxidation reactions of the chemical elements of which they consist, as well as by oxygen from air. As a result of regression analysis applied to define the properties of water vapor and gases, there have been derived linear and quadratic approximating dependences of the heat capacities of gases (CO2, N2) and water vapor (H2O) on temperature. There have been obtained the equations for determining the heat capacity of the combustion products of compressed gas for fuel grade A and B. There have been produced the formulas for determining heat capacity of pure combustion products of compressed gas ignited by the ignition diesel fuel. The obtained expressions are recommended to be used for analysis of the working cycle of a diesel engine running on the compressed gas.

Numerical Analysis on Reduction of Ultrafine Particulate Matter by a Kaolin Additive during Pulverized Coal Combustion

Adding additives into the furnace is an effective way to reduce particulate matter (PM) formed during coal combustion. However, a numerical model that can predict the performance of additives on PM reduction is still lacking. In this work, a numerical framework, which contains the submodels for ash formation and ash–additive interactions, was developed to predict the ash particle size distribution with and without kaolin additives. The model fully considers the physical–chemical reaction process between the combustion gaseous products (alkali metal vapor) and the Si-/Al-based adsorbent particles. The simulation results are validated by experimental measurements of PM formed during the combustion of high-sodium Zhundong coal on a lab-scale furnace. Given the typical conditions of the lab-scale furnace, adding 3% (by weight) kaolin reduces the mass yield of PM0.3 by 33.35% but has no obvious influence on PM>1. On the basis of a time-scale analysis, we show that the chemical adsorption of the mineral precursors is the dominant mechanism for PM reduction. The influences of the kaolin particle size and dosage on PM reduction are evaluated. The PM reduction efficiency quickly increases and then enters into a plateau as the kaolin mass ratio increases. When a certain critical value is reached, a further increase of the addition ratio has a negligible effect on PM reduction. The critical kaolin mass ratio is 4.1% for 2.1 μm of kaolin and quadratically increases to 4.9% for 21.3 μm of kaolin. Increasing the kaolin size, in contrast, has a negative impact on PM reduction. On the basis of the simulation results, it can be concluded that there exists an optimal condition for PM1 reduction by kaolin addition. The numerical framework developed in the current work can help to quickly find the optimal addition strategy under different additive/coal properties, combustion temperatures, and atmospheres.

Supercritical water partial oxidation mechanism of ethanol

In recent years, supercritical water as a green reaction medium to convert organic matter to produce hydrogen has attracted significant attention. At present, the mechanism of the supercritical water partial oxidation (SCWPO) process is still unknown when complete gasification is achieved. In this paper, a detailed mechanism for SCWPO of ethanol was proposed by establishing a novel kinetic model with a wide reaction temperature range. This model described the formation and consumption of gas products (H2, CO, CH4, and CO2) from ethanol by partial oxidation in the supercritical water environment through nine reactions. The results showed that the dehydrogenation and pyrolysis of ethanol were the main ways to generate H2 in the early stage, and the water-gas shift reaction had the most significant impact on hydrogen production in the later stage. The hydrogenation reaction of the intermediate product ethane was a key step for complete conversion into combustible gas products. The steam reforming reaction of a large amount of CH4 produced by ethanol and intermediate product will become the rate-determining step for hydrogen production.

Application of low-cost Fe-based catalysts in the microwave-assisted pyrolysis of macroalgae and lignocellulosic biomass for the upgradation of bio-oil

The combined application of microwave energy and special catalysts holds the potential for the selective conversion of biomass during the pyrolysis process. In this work, steel slag (SS) and biochar-based Fe (RHC/Fe) were adopted as both low-cost Fe-based catalysts and microwave absorbers in the microwave-heating pyrolysis system for the upgradation of bio-oil from macroalgae (Sargassum) and lignocellulosic biomass (pine sawdust). The catalysts all showed strong microwave adsorption performance, exhibiting higher heating rates than that of SiC. SS with a high content of iron oxides plays a catalytic role in biomass decomposition, while RHC/Fe with a highly porous structure not only promotes biomass decomposition but also enhances the secondary reaction of volatiles. The presence of SS significantly improved the content of lighter compounds (<C10 compounds) in Sargassum-derived bio-oil, leading to an improvement in the yield of potential chemicals such as phenols and furans; the formation of phenols was also significantly enhanced by SS during pine sawdust pyrolysis with a high phenols content of 55.8% in the obtained bio-oil. RHC/Fe exhibited remarkable selectivity on Sargassum pyrolysis and the obtained bio-oil contained only 13 compounds including 33.8% of <C10 compounds and 66.2% of >C20 compounds without any C10–C20 compounds. The N-containing compounds in Sargassum-derived bio-oil were successfully removed using RHC/Fe. RHC/Fe also showed a significant catalytic effect on the production of combustible gases from the pyrolysis of Sargassum and pine sawdust, with significant improvement in the total gas yields and combustible gas concentrations.

Research on the novel Al–W alloy powder with high volumetric combustion enthalpy

Abstract Al–xW alloy powder (x = 10, 20, 30, 40, 50 wt.%) was prepared by thermite reduction method and gas atomization method. The phase identification, surface morphology, spatial phase structure, oxidation behavior and combustion performance of the alloy powder were investigated by XRD, SEM/EDS, DSC, DTA/TG and oxygen bomb tests, respectively. The results show that among Al–xW alloy powder, Al–20W alloy powder has the largest volumetric combustion enthalpy measured in an oxygen bomb calorimeter (83,440 ± 790 J/cm3), which is superior to pure Al powder. Al–20W alloy powder has good sphericity and exhibits a special spatial phase structure, in which the metastable Al/W intermetallic compound is distributed in the pure Al matrix. In the process of stabilization, metastable phase transforms into the stable Al12W and release energy. The study of thermal oxidation behavior shows that Al–20W alloy powder has excellent thermal oxidation activity and oxidation completeness in air. Al–20W alloy powder is almost completely oxidized in air at 1500 °C, and only Al2O3 is detected in the oxidation product. The oxidation product particles of Al–20W alloy powder at 1500 °C are in the shape of a hollow shell. The combustion of Al–20W alloy powder produces a large amount of gaseous combustion product WO3, which is beneficial to increase the pressure inside the solid-propellant rocket engine. In summary, Al–W alloy powder has excellent application prospects in the field of energetic materials such as solid propellants and explosives.

Chemical compounds released by combustion of polymer composites flat belts

Machines and devices for the production, transport and segregation of products are placed in production and storage rooms. Flat conveyor and drive belts are very often used for their construction. Due to heavy loads and difficult operating conditions, these belts can catch fire and, as a result, become the main source of air contaminants harmful to human health and life. This article examines the emission level of toxic chemical compounds most often produced during the thermal decomposition and combustion of flat drive and conveyor belts. Six types of flat belts, which were made of various polymer materials, i.e., polyamide, rubber, and polyurethane, and were pyrolyzed in a tube furnace at 950 °C, were tested for emission. Using an Fourier transform infrared spectroscopy gas analyser, five gaseous products of combustion were identified, i.e., carbon mono oxide, carbon dioxide, hydrogen cyanide, hydrogen bromide and sulfur dioxide (SO2). Chemical analysis showed that SO2 compounds and hydrogen bromide were present in only two samples. The test results indicate that gas emission concentration limits for all the tested belts were significantly exceeded. A comparative analysis of the concentration limits of V-belts described in the authors' earlier works shows that flat belts demonstrate lower emission levels of harmful compounds than V-belts. In addition, research has shown that compared to traditional rubber-based belts, belts made of modern materials exhibit no emission of hydrogen chloride compounds during thermal decomposition and combustion.

A staggered-projection Godunov-type method for the Baer-Nunziato two-phase model

When describing the deflagration-to-detonation transition in solid granular explosives mixed with gaseous products of combustion, a well-developed two-phase mixture model is the compressible Baer-Nunziato (BN) model of flows containing solid and gas phases. As this model is numerically simulated by a conservative Godunov-type scheme, spurious oscillations are likely to generate from porosity interfaces, and may result from the average process of conservative variables that violates the continuity of Riemann invariants across porosity interfaces. In order to reduce numerical oscillations, this paper proposes a staggered-projection Godunov-type scheme over a fixed gas-solid staggered grid, by enforcing that compaction waves with porosity jumps are always inside gaseous grid cells and other discontinuities appear at gaseous cell interfaces. The scheme is based on a standard Godunov scheme for the Baer-Nunziato model on gaseous cells and guarantees the continuity of the Riemann invariants associated with the compaction waves across porosity jumps. While porosity interfaces are moving, a projection process fully takes into account the continuity of associated Riemann invariants and ensures that porosity jumps remain inside gaseous cells. Furthermore, the generalized Riemann problem (GRP) solver is applied, not only to achieve second-order accuracy, reduce numerical oscillations, but guarantees the well-balanced property of the resulting scheme as well.

Study on gasification characteristics of pine sawdust using olivine as in-bed material for combustible gas production

In order to reduce the tar content in the producer gas, a small-scale fluidized bed was built to gasify the pine sawdust with olivine as in-bed material. The impact of operating conditions, namely, temperature (700–850 °C), steam/biomass ratio (0.3–1.2), and olivine content (10%, 30% and 50%) was studied on the product gas composition, tar content, gas concentration and H2 yield. The main goal of the experiments was to determine the effect of the addition of olivine on the product gas composition and tar concentration. The results of the experiments confirm that steam-gasification of biomass with olivine can be a promising option for the production of H2-rich syngas with less tar formation as well as low CO2 emission. Under different temperatures, the gas yield and H2 yield are similar, higher at the higher temperatures but lower at the lower temperatures. A temperature rise from 700 °C to 850 °C increased the CO and H2 contents by 15.5% and 11%, respectively. The H2 yield increased from 35.4 to 57.2 g/kg as S/B ratio increased from 0.3 to 1.2. The highest H2 yield of 71.4 g/kg and the lowest tar concentration of 1.3 g/Nm3 were achieved at 800 °C, S/B ratio of 1.2 and olivine content of 50%.

ОПТИМІЗАЦІЯ НЕОРГАНІЧНИХ СКЛАДОВИХ ВОГНЕЗАХИСНОГО ЛАКУ ДЛЯ ДЕРЕВИНИ

Abstract. The processes of creation of fire-retardant varnish for wood consisting of a mixture of inorganic and polymeric substances are investigated in the work. It is established that the optimization of the inorganic component leads to a directional ratio of mineral acids and urea capable of effective fire protection of the material. Studies have shown that at the initial temperature of gaseous combustion products T = 68 °C, when exposed to the radiation panel, the untreated sample ignited after 146 s, the flame spread over the entire surface, instead, the sample fire-protected varnish did not ignite, the maximum temperature was 105 °C. In this case, as evidenced by the results of heat resistance, there is a change in the structure of the protective film of the coating. The thickness of the protective layer increases due to the decomposition of the composition, which leads to inhibition of oxidation in the gas and condensed phase, change the direction of decomposition towards the formation of non-combustible gases and combustible coke residue, reduce material combustion and increase flammability index. The coating under the influence of high temperature promotes the formation of a heat-insulating layer of coke, which prevents burning and the passage of high temperature to the material, which is confirmed by the absence of the process of ignition of fire-retardant wood. Features of braking of process of ignition and distribution of a flame of the wood processed by a varnish which consist in several aspects are established. This is the formation of a heat-insulating layer of coke, which prevents burning and the passage of high temperatures to the material, which is confirmed by the absence of the process of ignition of fire-retardant reeds. This indicates the possibility of targeted control of high temperature transfer processes to organic material through the use of special coatings for wood products.

Development and thermal behavior of a new type of polymer materials with reduced combustibility based on epoxy–amine composites modified with copper(II) hexafluorosilicate

The polyamine chelate complex of copper(II) hexafluorosilicate—[Cu(eda)(deta)]SiF6—(a flame retardant-hardener of epoxy resins) and CuSiF6-containing epoxy–amine composites—DGEBA/pepa-CuSiF6—with reduced combustibility and with the varied content of CuSiF6 were obtained in the DGEBA–pepa–CuSiF6 system (pepa—H2N[–C2H4NH–]nH, n = 1 (eda—NH2C2H4NH2) and n = 2 (deta—NH2C2H4NHC2H4NH2); DGEBA—bisphenol A diglycidyl ether). These samples were characterized by IR spectra, thermal analysis and flammability studies. The results of Thermogravimetric analysis (TGA) showed that thermal decomposition of [Cu(eda)(deta)]SiF6 is completed at 368 °C and the maximal temperature of the gaseous combustion products was 488 °C. TGA data for DGEBA/pepa-CuSiF6(22) confirm that the incorporation of [Cu(eda)(deta)]SiF6 into DGEBA significantly increases thermal stability and anti-flammability of CuSiF6-containing epoxy–amine composites. Ignition and self-ignition temperatures have been measured for all CuSiF6-containing epoxy–amine composites in accordance with ASTM D1929-16. Depending on the quantity of added CuSiF6, the tignition for this type of composite increases by 15–34 °C, and the tself-ignition increases by 25–58 °C compared to DGEBA/pepa. The flammability of the samples was evaluated by means of UL94 BH methods. The burning rate of the DGEBA/pepa-CuSiF6(66) and DGEBA/pepa-CuSiF6(88) epoxy–amine composites is severe slowed down (these samples do not propagate flame), while rburn. value for the unmodified epoxy–amine sample (DGEBA/pepa) is 25.13 mm min−1.

Direct numerical simulation of turbulent boundary layer premixed combustion under auto-ignitive conditions

In the present work, premixed combustion in a turbulent boundary layer under auto-ignitive conditions is investigated using direct numerical simulation (DNS). The turbulent inflow of the reactive DNS is obtained by temporal sampling of a corresponding inert DNS of a turbulent boundary layer at a location with Reτ= 360, where Reτ is the friction Reynolds number. The reactants of the DNS are determined by mixing the products of lean natural gas combustion and a H2/N2 fuel jet, resulting in a lean mixture of high temperature with a short ignition delay time. In the free stream the reaction front is stabilized at a streamwise location which can be predicted using the free stream velocity U∞ and the ignition delay time τig. Inside the boundary layer, combustion modifies the near-wall coherent turbulent structures considerably and turbulence results in reaction front wrinkling. The combustion modes in various regions were examined based on the results of displacement velocity, species budget and chemical explosive mode analysis (CEMA). It was indicated that flame propagation prevails in the near-wall region and auto-ignition becomes increasingly important as the wall-normal distance increases. The interactions of turbulence and combustion were studied through statistics of reaction front normal vector and strain rate tensor. It was found that the reaction front normal preferentially aligns with the most compressive strain rate in regions where the effects of heat release on the strain rate are minor and with the most extensive strain rate where its effects are significant. Negative correlations between the wall heat flux and flame quenching distance were observed. A new quenching mode, back-on quenching, was identified. It was found that the heat release rate at the wall is the highest when head-on quenching occurs and lowest when back-on quenching occurs.

АНАЛИЗ ТРЕБОВАНИЙ К ТВЕРДОТОПЛИВНЫМ ГАЗОГЕНЕРАТОРАМ ДЛЯ СИСТЕМ ПОДАЧИ ПОРОШКООБРАЗНОГО ТОПЛИВА РЕАКТИВНЫХ ДВИГАТЕЛЕЙ

The existing sources of the operating fluid used in aviation and rocket-space technology are analyzed. The disadvantages of inert gas cylinders used as a source of the operating fluid of the component supply system in jet engines are considered. An alternative to the gas pressure system is a low temperature solid propellant gas generator (LTGG) with a coolant. Controllable powdery components supply scheme of an air-breathing engine (ramjet) is proposed. The principle of operation of such a feeding scheme is described. To ensure the stability of the output characteristics of the LTGG, a valve system is used. The requirements for the gas source and combustion products (CP) involved in the operating process have been determined. The analysis of the existing methods of cooling the CP is carried out. It was revealed that the low-temperature solid-propellant gas generator with a powdery capacitance coolant meets the most fully the above requirements, the principle of operation, which is based on the heat transfer wave localization effect. Solid propellant with the following composition: 38 % AP + 38 % Octogen + 24 % SKI-NL is selected. The CP temperature, at a pressure in the combustion chamber of 6 MPa, is 1545 K, and the CP gas constant is 459.4 J / kg·K, the condensed phase is absent, and the water vapor content in the operating fluid does not exceed 1.6 %. The combustion of the proposed propellant produces a significant amount of combustible components – 60 % CO, 4 % H2, &gt; 1 % CH4. The use of valves on cold gas ensures the reliability of the controlled supply system of powder components, and, accordingly, the entire engine. Based on the results of the work, conclusions were made about the correspondence of the obtained parameters of solid propellant and LTGG to all the requirements set.

Combustion optimization in gas burners of reverberatory furnaces during the melting of nickel alloys

In recent years, due to climate change environmental sustainability programs have been created that require the search for alternatives to reduce air emissions and reduce fuel consumption. The combustion industry is looking for an effective solution to increase the life cycle of its equipment and improve combustion efficiency without neglecting safety or savings. The efficiency of the medium pressure natural gas burners associated with chemical energy, which is converted into heat, that is, the hotter the gaseous products of combustion, the more efficient the burner. The work analyzes the combustion process and their chemical reactions; combustion products obtained in accordance with various conditions; combustion characteristics and factors that influence; and measurement methods needed to optimize combustion and their equipment. In the metallurgical production of nickel, optimization of the burners is very important due to the high temperature used in the reverberatory furnace. That is, the use of a large excess of air would be unfavorably energetic, and the use of a very low excess would result in small intimate mixtures of air and fuel, followed by the release of unreacted reagents and the formation of toxic gases arising at high temperatures. For this reason, the results of this work are an important source of information. The innovation is to automate the use of non-invasive sensors to control the combustion process. The sensors play a fundamental role in the industry, because the information they provide supports the enhanced use of data in the enterprise, increase productivity, efficiency and safety.

Environmental efficiency investigation of a gas turbine unit

A method for purifying the gas-air mixture of a gas turbine unit and a waste-heat boiler is considered [1-3]. This work describes the principle of a gas-turbine plant and a waste-heat boiler operation using a catalytic afterburner, with the help of which a more complete process of carbon dioxide and nitrogenous compounds release occurs. Also, as a result of the exhaust gas-air mixture deeper cleaning process, there is a decrease in emissions within the maximum admissible concentrations (MAC), namely, by the amount of nitrogen and carbon oxides [4–7]. That allows to reduce the number of harmful substances, oxides of nitrogenous and carbon compounds, emitted into the environment. A scheme for cleaning a catalytic afterburner using rotary mesh devices, followed by disposal of carbon deposits and soot substances from the cleaning chamber is shown. This makes it possible to perform a stable ion exchange process, reducing the exhaust gases combustion products amount. It is proposed in this article to use mesh devices in the afterburner, treated with active substances by the method of ion implantation, as one of the most promising methods for modifying mesh surfaces. These processes occurring when the gas-air mixture passes through the afterburner, can reduce MAC emissions for various options for utilizing the discharge fuel mixture of a gas turbine unit (GTU) and heat supply to the waste heat boiler.

A comprehensive study on laminar burning velocity and flame stability of oxy-producer gas mixtures. Part-2: Laminar burning velocity and Markstein length analysis

Part-1 reported the extent of variation in each species in producer gas (PG) mixture(s) after a thorough literature study. Forty-five PG variants were identified to analyse the effect of each species on the combustion characteristics of PG-O2 mixtures. Spherical flame method was used for measuring laminar burning velocities and burned gas Markstein lengths of PG at 1 bar, 300 K and ϕ = 0.8 in a 4.5 L spherical chamber. Extrapolation (linear and non-linear) and non-extrapolation based schemes were used to estimate unstretched flame speed. LBV extracted from all three schemes were in good agreement within ±4.92%. Only H2/CO-rich-PG-O2 mixtures having mole fraction of combustible components (CC) less than 20% displayed negative Lb values and their effective Lewis numbers were less than the respective critical values and were corroborated with experimental results. CH4-rich-PG-O2 mixtures were unconditionally stable. Their LBV was the highest at most conditions due to high flame temperatures, with exception to LBV of H2-N2-rich-PG-O2 mixtures at 45%CC owing to large thermal diffusivities. LBV varied non-linearly as CO2 in non-combustible components (NCC) increased beyond 50% and its suppressing effect was the highest in CH4-rich-PG. Simulations were performed using 1D expanding spherical flame model in COSILAB with GRI-Mech3.0. Simulated LBV showed a deviation of ±13.2% with experimental values at 45%CC. Unstretched LBV obtained from non-extrapolation-mapping method which involved simulation results showed good agreement with experiments. Combustion of PG with higher H2, CO and N2 content and relatively lesser amounts of CH4 and CO2 were stable to preferential diffusion effects and predictable to fluctuations in composition.