Flue Gas Analyzer Research Articles

Spray characteristics of steam-assisted oil atomization in Y-jet nozzles

Twin-fluid atomizers, valued for handling viscous fluids and high operating loads, are extensively used in combustion processes and oil refineries. In the latter scenario, internal mixing nozzles are employed in fluid catalytic cracking units for oil dispersion using steam as the dispersing medium. While steam-assisted atomization studies often focus on flue gas analysis, the associated steam/oil internal mixing process and the spray droplet dynamics lack proper investigation. Accordingly, this work explores the Y-jet nozzle performance for oil atomization using steam, aiming to determine favorable conditions for obtaining a stable spray with fine droplet distribution. This analysis is accomplished by characterizing the mixing chamber pressure, investigating the spray boundary instabilities using high-speed images, and exploring the spray droplet size using the shadowgraphy technique. Work relevance relies on performing experiments at industrially representative conditions, characterized by the similarity of important dimensionless numbers. Additionally, the nozzle design is optimized by varying key geometric parameters. The nozzle geometry and the operating condition impact on the steam-assisted atomization performance and spray behavior constitutes the main findings of this work. The outcomes highlight the relevance of the fluid dynamics investigation for optimized nozzle performance, involving a balance between spray stability and fine droplet distribution generation.

Detection of ultra-low concentration NH3, SO2, and NO using UV-DOAS combined with multidimensional spectral fusion

Since nitric oxide (NO), sulfur dioxide (SO2), and ammonia (NH3) in flue gas cause severe air pollution, accurate measurements of their concentrations are crucial for optimizing the efficiency of flue gas denitrification in coal-fired power plants and protecting the atmosphere. Due to their large absorption cross sections in the ultraviolet (UV) band, NH3, SO2, and NO in flue gas can be detected by UV Differential Optical Absorption Spectroscopy (UV-DOAS) techniques. However, spectral overlap and noise caused by short optical path limitations in the measurement are the main obstacles to achieve concentration inversion. Here, we propose a multidimensional spectral fusion method one-dimensional convolutional neural network combined with two-dimensional convolutional neural network (1D-2D-CNN) with the ability to invert concentration of NH3, SO2 and NO at ppb level with 0.5 m optical-length. To separate the absorption features, one-dimensional spectra are converted into two-dimensional time-frequency plots by continuous wavelet transform (CWT). After denoising the spectra by wavelet thresholding, one-dimensional and two-dimensional spectral features are extracted by 1D-2D-CNN model and fused for inversion. The experimental results show that the proposed system can effectively eliminate interferences from NH3, SO2, and NO, significantly improving the concentration inversion accuracy. The detection limits for NH3, SO2 and NO in the mixture are 0.95 ppb∙m, 6.31 ppb∙m, and 2.53 ppb∙m, respectively, demonstrating that our approach outperforms other reported methods for flue gas analysis. The proposed system is expected to be applied to ammonia slip monitoring of Selective Catalytic Reduction (SCR) in power plants.

Innovative Method of Biomass Combustion in the Binary Fluidised Bed

Abstract In this study, a binary fluidised bed made out of quartz sand and cenospheres for the biomass combustion process was created. Materials were fluidised with air to achieve a vertical density profile (from 0.5 g/cm³ to 1.1 g/cm³) resulting from grains segregation. The density profile was selected to ensure optimal control over the location of the combusted fuel particle. This involved positioning the process as close to the bottom sieve as possible. Fluidised bed combustion was carried out at temperatures of 600 °C, 700 °C, 820 °C and 870 °C using straw, willow and sawmill pellets as fuels. Qualitative and quantitative analysis of flue gases was performed using an FTIR spectrometer. Over 90 % carbon conversion from the biomass to carbon dioxide was achieved at 700 °C. At 820 °C and 870 °C, 100 % of biomass carbon left the reactor as CO2. The composition of organic compounds in the process products remained low, reaching a maximum of 3.0 % wt. at 600 °C. To gain further insights into the processes occurring in the immediate vicinity of biomass samples, a complementary TGA/FTIR analysis was conducted. This aimed to clarify the impact of the biomass particle decomposition stage in the fluidised bed combustion process. The proposed mechanism for biomass combustion in the binary fluidised bed contains the particle decomposition stage and the subsequent stage resulting from the coalescence of bubbles containing flammable components and bubbles containing oxidiser.

A novel and clean utilization of flue gas desulfurization ash coupled with converter sludge to produce calcium ferrate

To address the environmental pollution from industrial wastes like desulfurization ash (DA) and converter sludge(CS), this study introduces a novel method for synthesizing calcium ferrate. This method involves reacting converter sludge with desulfurization ash at high temperatures, facilitating the concurrent elimination of toxic elements. The solid byproduct is suitable as a sintered ore additive, while the gaseous SO2 serves as a precursor for sulfuric acid production. Additionally, the metal-rich secondary dust offers a source for valuable metal recovery. This research employs simulation software (FactSage 8.1) and thermal analysis to explore the high-temperature reaction dynamics of converter sludge and desulfurization ash. Subsequent in-situ experiments and coupled high-temperature tube furnace-infrared flue gas analysis further elucidated the phase transitions, morphology changes, flue gas emissions, and migration of harmful elements (e.g., S, K, Na, Pb, Zn). Analysis using the Predom dominant zone module calculation indicates that low SO2 concentration and reduced oxygen levels promote the stability of Ca2Fe2O5. Infrared flue gas analysis reveals high concentrations of CO2 and SO2. Sulfur removal rates rose from 62.15 % to 98.48 % between 800 °C and 1100 °C. Removal efficiencies for alkali and heavy metals, namely K, Na, Pb, and Zn, improved significantly, reaching 99.95 %, 99.49 %, 99.71 %, and 86.7 % respectively. At 1100 °C under an N2 atmosphere, the main reaction products from Flue Gas desulfurization ash (FGDA) and converter sludge were CaFe3O5 and Ca2Fe2O5. This study’s comprehensive analysis of synthesizing calcium ferrate from Flue Gas desulfurization ash and converter sludge introduces a novel waste utilization method, offering substantial environmental and economic advantages.

Effect of burner structural parameters on combustion characteristics and NOx emission of natural gas

The low-nitrogen combustion of natural gas has always been a crucial topic in environmental protection. Currently, small and medium-sized industries use straight-through pipelines as their burner nozzles. This design results in poor heat diffusion capacity after mixed combustion and a long time of temperature diffusion, leading to low combustion efficiency and high NOx emissions. To address this issue, a new type of natural gas low-nitrogen burner with a multi-port diffusion nozzle was developed. The burner’s structure was optimized through a combined approach of experiment and numerical simulation. The optimal structural parameters for the burner are a 40° swirl angle and 8 swirl blades, as indicated by the numerical simulation research results. The designed multi-port diffusion nozzle is matched with the appropriate swirl angle and number of blades to promote natural gas diffusion, forming an annular space region flames and a stable flame shape with a height of 0.64 m. After optimization, the average concentration of NOx at the outlet of the combustion chamber decreased from 61.5 ppm to 20.81 ppm. A natural gas low-nitrogen combustion experimental system was designed and constructed based on simulation results. The experimental results were analyzed in terms of flame structure characteristics, temperature distribution, and NOx emissions. The results indicate that the trend in temperature change is consistent with the simulation process. The NOx concentration at the outlet of the combustion chamber was measured by the flue gas analyzer to be 34.1 ppm, which was 5.3 ppm lower than the NOx concentration calculated by numerical simulation. The new burner exhibited better flame stability and a 12.6 % reduction in NOx emissions compared with a traditional straight-through pipeline burner of the same size. The designed natural gas low-nitrogen burner appears to be a suitable device for reducing NOx emissions in small and medium-sized industries.

Investigation of Combustion and NO/SO2 Emission Characteristics during the Co-Combustion Process of Torrefied Biomass and Lignite.

This paper investigates the combustion characteristics and pollutant emission patterns of the mixed combustion of lignite (L) and torrefied pine wood (TPW) under different blending ratios. Isothermal combustion experiments were conducted in a fixed bed reaction system at 800 °C, and pollutant emission concentrations were measured using a flue gas analyzer. Using scanning electron microscopy (SEM) and BET (nitrogen adsorption) experiments, it was found that torrefied pine wood (TPW) has a larger specific surface area and a more developed pore structure, which can facilitate more complete combustion of the sample. The results of the non-isothermal thermogravimetric analysis show that with the TPW blending ratio increase, the entire combustion process advances, and the ignition temperature, maximum peak temperature, and burnout temperature all show a decreasing trend. The kinetic equations of the combustion reaction process of mixed gas were calculated by Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) kinetic equations. The results show that the blending of TPW reduces the activation energy of the combustion reaction of the mixed fuel. When the TPW blending ratio is 80%, the activation energy values of the mixed fuel are the lowest at 111.32 kJ/mol and 104.87 kJ/mol. The abundant alkali metal ions and porous structure in TPW reduce the conversion rates of N and S elements in the fuel to NO and SO2, thus reducing the pollutant emissions from the mixed fuel.

First experimental realization of a thermoacoustic-based flue-gas analyzer

Flue-gas analyzers are critical for various applications, including the optimization of combustion efficiency and air quality monitoring. While capable of accurately measuring gas concentrations, current sensors require frequent calibration, suffer short lifespans, and can be susceptible to inference from trace gases. In this report, we provide a first physical implementation of a thermoacoustic-based gas analyzer by investigating the sensitivity of a standing-wave thermoacoustic engine to variations in three different flue-gas components, CO2, O2, and N2. Experimentally measured shifts in both the onset temperature difference and the fundamental resonance frequency with varying gas compositions confirm the feasibility of a thermoacoustic system for flue-gas analysis. The presented data paves the way for further exploration of this innovative approach, offering an efficient and cost-effective acoustic-based alternative to existing flue-gas analysis methodologies.

Predictive modeling of engine performance and emissions for castor oil ethyl ester biodiesel blends: A Gaussian process regression approach

Replacing fossil fuels with cleaner alternatives is essential. This study examines a biodiesel-diesel blend containing 8 % castor oil ethyl ester (COEE8) and its impact on engine performance, combustion characteristics, and exhaust emissions. A single-cylinder diesel engine was tested under consistent conditions: an engine speed of 1500 rpm, varying engine loads (25 %, 50 %, and 75 % of maximum torque), and compression ratios (16, 17, and 18). Engine-out emissions were measured with Testo flue gas analyzers. The results showed that COEE8 combustion significantly decreased HC, CO, and smoke emissions compared to diesel fuel but increased NOx emissions. Additionally, COEE8 exhibited comparable brake-specific fuel consumption (BSFC) and brake thermal efficiency (BTE) to diesel fuel. The optimal engine operating parameters were determined using the Non-dominated Sorting Genetic Algorithm-II (NSGA-II), a multi-objective optimization technique. Due to limited data availability, Gaussian Process Regression (GPR), a machine learning algorithm for small datasets, modeled the multi-objective functions with compression ratio and engine load as input variables. The GPR model demonstrated high prediction performance across all output parameters (BSFC, BTE, HC, smoke, NOx, and CO) for both diesel and COEE8 fuels, with average coefficients of determination (R2) of 0.9896 and 0.9953, respectively, indicating a strong correlation between predicted and actual values. The mean absolute percentage error (MAPE) was also low, averaging 3.11 % and 2.26 %, respectively, demonstrating the model's accuracy. Using the GPR model, the NSGA-II identified the optimal trade-off between NOx and smoke index for both diesel and COEE8 fuels. The optimal compression ratio was 16 for both fuels, while the optimal engine load varied, ranging from 20 % to 30 % for COEE8 and around 30 % (almost 40 %) for diesel fuel.

Multi-Criteria Optimization of a Laboratory Top-Lit Updraft Gasifier in Order to Reduce Greenhouse Gases and Particulate Matter Emissions

Air pollution from combustion processes is harming human health and the environment. To mitigate this, one needs to adopt cleaner energy production methods, in particular, to optimize combustion systems in order to minimize pollutants and increase efficiency. Flue gas analysis and particulate matter (PM) monitoring, starting from the prototype phase, is crucial to minimize and regulate pollutant emissions. This article analyses the emissions of pollutants and particulate matter from a combustion test gasifier working on the Top-Lit Updraft (TLUD) principle in order to optimize functionality and reduce exhaust emissions. Three experiments were performed in which the primary (gasification) air flow rate (GA) was kept constant at 25 L/min, and the secondary (combustion) air flow rate (CA) was adjusted to obtain a CA/GA ratio of 2 (50 L/min), 3 (75 L/min), and 4 (100 L/min) respectively. Based on a multi-criterial analysis, the optimal CA/GA ratio for TLUD combustion is 3, offering a well-rounded performance in output temperatures, PM and greenhouse gases (GHG) emissions, and efficiency, while the CA/GA ratio of 4 has good PM and GHG emissions performance but lower efficiency, and the CA/GA ratio of 2 is the least favorable due to its poor performance in output temperatures, PM and GHG emissions.

Production and emission characterization of briquette for sustainable development: MSW transformation.

Global community is increasingly alarmed by resource depletion and environmental pollution. In light of pressing environmental concerns and depletion of finite resources, the surge in fossil fuel usage has sparked twin crises: dwindling fossil fuel reserves and escalating environmental pollution. The current study introduces a novel approach to minimize waste by transforming it into briquettes suitable for large-scale production. Production of briquettes involves multiple stages, including collection, drying, crushing, screening, blending, compacting, and storage. The main objective of this research is to demonstrate and investigate the physico-mechanical and emission properties of briquettes produced with readily available organic fraction of municipal solid waste (MSW) such as food and garden waste. The physical, mechanical, and elemental characteristics such as calorific value, moisture content, ash, volatile matter, fixed carbon, density, compressive strength, and SEM-EDAX were determined. A combustibility test along with emission and water boiling test was also carried out. The MSW briquettes were prepared in a densification system at 130°C temperature and 20MPa. The study's conclusion suggests that the MSW briquette with lignin content of 25-30%, calorific value of 22.53MJ/kg, compressive strength of 14.517 N/mm2, and density of 1124.12kgm-3 could be used to retain energy and lessen the harmful effects of climate change while also enhancing sustainability. Flue gas emissions from burning MSW briquettes in a biomass stove were examined in this study using flue gas analyzer and smoke meter. Furthermore, the generated briquettes exhibit a density of 1124.12kgm-3 which is on par with coal, making them suitable for co-firing in boilers. Likewise, the determined parameters are compared with the biomass briquettes and firewood. Further investigation is required to elevate its quality and economic potential.

Experimental Research on an Afterburner System Fueled with Hydrogen–Methane Mixtures

A new afterburner installation is proposed, fueled with pure hydrogen (100%H2) or hydrogen–methane mixtures (60% H2 + 40% CH4, 80% H2 + 20% CH4) for use in cogeneration applications. Two prototypes (P1 and P2) with the same expansion angle (45 degrees) were developed and tested. P1 was manufactured by the classic method and P2 by additive manufacturing. Both prototypes were manufactured from Inconel 625. During the tests, analysis of flue gas (CO2, CO, and NO concentration), PIV measurements, and noise measurements were conducted. The flue gas analysis emphasizes that the behavior of the two tested prototypes was very similar. For all three fuels used, the CO2 concentration levels were slightly lower in the case of the additive-manufactured prototype P2. The CO concentration levels were significantly higher in the case of the additive-manufactured prototype P2 when 60% H2/40% CH4 and 80% H2/20% CH4 mixtures were used as fuel. When pure H2 was used as fuel, the measured data suggest that no additional CO was produced during the combustion process, and the level of CO was similar to that from the Garrett micro gas turbine in all five measuring points. The NO emissions gradually decreased as the percentage of H2 in the fuel mixture increased. The NO concentration was significantly lower in the case of the additive-manufactured prototype (P2) in comparison with the classic manufactured prototype (P1). Examining the data obtained from the PIV measurements of the flow within the mixing region shows that the highest axial velocity component value on the centerline was measured for the P1 prototype. The acoustic measurements showed that a higher H2 concentration led to a reduction in noise of approximately 1.5 dB for both afterburner prototypes. The outcomes reveal that the examined V-gutter flame holder prototype flow was smooth, without any perpendicular oscillations, without chaotic motions or turbulent oscillations to the flow direction, across all tested conditions, keeping constant thermal power.

Early fire detection technology based on improved transformers in aircraft cargo compartments

The implementation of early and accurate detection of aircraft cargo compartment fire is of great significance to ensure flight safety. The current airborne fire detection technology mostly relies on single-parameter smoke detection using infrared light. This often results in a high false alarm rate in complex air transportation environments. The traditional deep learning model struggles to effectively address the issue of long-term dependency in multivariate fire information. This paper proposes a multi-technology collaborative fire detection method based on an improved transformers model. Dual-wavelength optical sensors, flue gas analyzers, and other equipment are used to carry out multi-technology collaborative detection methods and characterize various feature dimensions of fire to improve detection accuracy. The improved Transformer model which integrates the self-attention mechanism and position encoding mechanism is applied to the problem of long-time series modeling of fire information from a global perspective, which effectively solves the problem of gradient disappearance and gradient explosion in traditional RNN (recurrent neural network) and CNN (convolutional neural network). Two different multi-head self-attention mechanisms are used to classify and model multivariate fire information, respectively, which solves the problem of confusing time series modeling and classification modeling in dealing with multivariate classification tasks by a single attention mechanism. Finally, the output results of the two models are fused through the gate mechanism. The research results show that, compared with the traditional single-feature detection technology, the multi-technology collaborative fire detection method can better capture fire information. Compared with the traditional deep learning model, the multivariate fire prediction model constructed by the improved Transformer can better detect fires, and the accuracy rate is 0.995.

Feasibility of co-disposal of lignite and eucalyptus wood in coal-fired power plants: thermogravimetric characterization, typical gaseous pollutant emission characteristics, and economic analysis

ABSTRACT Energy issues are becoming increasingly prominent, and biomass blending in coal-fired power plants can improve combustion performance and reduce gaseous pollutant emissions, thereby improving economic efficiency. In this study, a thermogravimetric analyzer, a horizontal tube furnace, and an infrared flue gas analyzer were used to investigate the combustion behavior and gaseous pollutant emissions of the co-combustion of LC and EW. The results show that blending EW into LC cofiring can inhibit the release of volatile matter and promote the decomposition of fixed carbon and lignin simultaneously. The HHV of EW (15.88 MJ/kg) reaches 63.7% of LC’s (24.90 MJ/kg), indicating EW has a high energy utilization value. With increasing combustion temperature, the average value of CR S increased from 47.09% to 59.94%, and the average value of CR Cl increased from 26.15% to 52.15%, leading to a significant increase in SO2 and HCl emissions. The decrease in combustion temperature slightly promoted the release of N (CR N increased from 11.76% to 14.45%). The results of the economic analysis show that the cost of CaO and NH3·H2O used for removing gaseous pollutants decreased the most, and the economic efficiency increased the fastest to 14,000 RMB/day when the EW blending ratio increased from 10% to 20%.

Synergistic reduction on PM and NO source emissions during preheating-combustion of pulverized coal

The present research focuses on the synergistic source control of particulate matter (PM) and NOx formation from pulverized coal combustion. Comparative experiments of preheating-combustion and conventional combustion were conducted in a lab-scale high-temperature preheating-combustion furnace, and PM10 and NO were measured by an electrical low pressure impactor and a flue gas analyzer, respectively. The results of the experiment indicate that preheating-combustion has a significant reduction in PM10 (especially PM0.3 up to 37.51 %) and NO, which can achieve the synergistic control of PM10 and NO source emissions during the combustion process. The fragmentation in preheating-combustion was weaker compared to the conventional combustion. Meanwhile, the relatively weak preheating-combustion coal char oxidation reaction leads to a decrease in ultrafine mode PM yielded due to the inhibition on vaporization of mineral inclusions. The PM0.3/PM1 mass ratio of the preheating-combustion has a decreasing trend, implying an elevated yield of PM0.3-1 and a shift of the average PM1 particle size toward a larger particle size. Higher preheating temperature (Tp) presented the potential to further reduce NO formation, and the NO reduction efficiency increased from 46.59 % to 56.60 % when the Tp was increased from 1200 K to 1600 K. All our preliminary results throw light on the nature of synergistic source control of preheating-combustion PM and NO formation.

Pilot Demonstration of a New Tip for Effective Gas Flaring in the Permian Basin: Part 1.

In the oil and gas industry, gas flaring through flare stacks plays a critical role in safely and efficiently releasing and burning gases and other materials from pressure-relief and vapor-depressurizing systems. Gas flaring is a contentious and formidable environmental challenge, both regionally and globally. Its adverse impacts encompass pollution, contribution to global warming, and substantial economic losses. Shockingly, gas flaring squanders approximately 5% of the global gas supply, resulting in the annual production of over 350 million tons of CO2 gas. While alternatives to gas flaring exist, they are either undergoing investigation or currently lacking economic viability. Consequently, the development of a more efficient gas flaring system is imperative. In addition, the reliable and efficient operation of flares is paramount, as they are expected to function seamlessly over extended periods under various service conditions. In this paper, a novel gas flaring tip to address the limitations of existing flaring systems is introduced. This innovative tip features a distinctive configuration, incorporating a bullet-shaped device positioned atop the flare. This bullet device boasts four strategically placed apertures equipped with internal deflectors, facilitating the convergence of gases into a single vortex outlet at its apex. For operational flexibility, the bullet is affixed to the flare tip using a system of three springs, enabling it to elevate at a pressure of 2.0 psig and achieve full extension at 8 psig. This dynamic design harnesses the Coanda effect, promoting efficient oxygen utilization. The comprehensive evaluation of this tip spanned a wide range of gas capacities, 4.0 and 10.0 MMSCFD. In this analysis, parameters such as the fraction of heat radiated, transmissivity, atmospheric humidity level, solar radiation adjustment, ambient temperature, and horizontal wind velocity were factored. The evaluation included both theoretical analysis and experimental investigation. The theoretical analysis employed a simplified open pipe flare tip approach to predict thermal radiation levels around the tip using the Brzustowski and Sommer model. The experimental setup included equipment such as thermocouple thermometers, heat flux sensors, digital sound level meters, mass flowmeters, and portable flue gas analyzers. Throughout testing, thermal radiation levels, isopleths, noise levels, and flue gas composition were measured. The collected data were subsequently compared to predictions generated using the Brzustowski and Sommer model for identical gas flow rates, flare heights, and flare diameters. Due to technical challenges and safety concerns, flue gas composition was not available. The authors are exploring different alternatives to overcome these obstacles and data should be available in the near future. The resulting data of heat radiation and noise levels unequivocally demonstrate the superiority of the new tip when compared to conventional gas flaring systems. With its cost-effectiveness, smokeless operation, heightened efficiency, and cleaner flame characteristics, the authors, due to the groundbreaking design of this tip, strongly advocate its adoption as a means to mitigate the environmental impact of gas flaring.

Experimental Study on Combustion Efficiency and Pressure Gain Characteristic of RDC with Guide Vanes

ABSTRACT The influence of guide vanes on the combustion efficiency and pressure gain characteristic of rotating detonation combustor was studied. In this experiment, aviation kerosene (RP-3) was used as fuel and hot air was used as oxidant under the condition of maintaining a certain air flow of 1.5 kg/s. The Temperature rise method was used and the combustion products were analyzed by the flue gas analyzer to calculate the combustion efficiency. Pressure gain characteristic of the rotating detonation combustor was calculated by the mass flow function method (MFFM). The detonation was successfully initiated and operated stably in two rotating detonation combustor configurations without guide vanes and with guide vanes installed. Without the guide vanes, the equivalent ratios for reliable operation of the rotating detonation combustor were relatively small, and the mode of detonation wave propagation is mainly two-counter rotating wave mode. Behind the guide vanes were installed, the range of equivalent ratios for reliable operation of the rotating detonation combustor moved to the appropriate chemical equivalent ratio, and the main mode of detonation wave propagation is two-co rotating wave mode. When the guide vanes were installed, the combustion efficiency of the rotating detonation combustor reached the maximum value of 60.29% when the equivalence ratio is 0.78. In both combustor structures, the pressure gain characteristic increased with the increase of equivalence ratio.

Enhanced NOx reduction through reburning of potassium chloride doped biomass at intermediate temperature in oxy-biomass combustion

The challenge of achieving low nitrogen oxide (NOx) emissions in carbon-negative oxy-biomass combustion remains significant. This study focuses on enhancing NOx reduction by doping washed biomass with varying ratios of potassium chloride (KCl) to determine the optimal quantity for maximum NOx reduction. Unlike the traditional high-temperature reburning method used in PC furnaces (above 1000 °C), this study explores reburning at intermediate temperatures (550–850 °C) to assess its feasibility in fluidized bed or grate fired furnaces. Flue gas analysis is performed using an FTIR gas analyzer (Gasmet DX-4000, Finland), while solid residue analysis utilizes SEM-EDS, XRD, XRF, and TGA techniques. Results demonstrate that the highest NO reduction efficiency, up to 80 %, is achieved at a stoichiometric ratio of 0.6, a temperature of 700 °C, and 1.5 % KCl doping in an oxygen-rich environment. These findings highlight the effectiveness of a small amount of KCl doping (1.5 %) in catalyzing heterogeneous NO reduction reactions for enhanced NO reduction. Furthermore, this same KCl doping quantity (1.5 %) effectively suppresses the formation of harmful substances such as HCN and N2O, thus improving the conversion of NO to N2. Overall, this study provides valuable insights for the development of NOx control methods in intermediate temperature oxy-biomass combustion systems.

Effect of ferrocene as a combustion catalyst on the premixed combustion flame characteristics of Jatropha biodiesel

Fuel additives are widely used to optimize the combustion process, reduce the harmful emissions, and improve the performance of engines. Among the metal-based additives, ferrocene is soluble in most fuels, including biodiesel. Furthermore, it is easily available and has high stability, low toxicity, and high lipophilicity. It can evenly disperse in biodiesel without causing any change in the physicochemical properties. Therefore, it can serve as an effective combustion catalyst for biodiesel. In this study, the effect of ferrocene as a combustion catalyst on the pyrolysis and combustion performance of Jatropha biodiesel is investigated. The coupled technique of thermogravimetry-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS) is used to analyze the evolution characteristics of multicomponent gaseous products generated during the pyrolysis and high-temperature oxidation of Jatropha biodiesel (JB100) and Jatropha biodiesel + ferrocene (JBF). The laminar premixed combustion flame and pollutant emissions of JB100 and JBF are examined using a variety of techniques, including OH planar laser-induced fluorescence (OH-PLIF), flue gas analysis, spectral analysis, transmission electron microscopy, etc. The results reveal that after adding ferrocene, the activation energy for the pyrolysis reaction of JB100 decreases by 4.66 kJ/mol and the complete weight loss temperature decreases by 10 ℃. Further, the addition of ferrocene reduces the endothermic heat by 0.38 mW/mg during the initial stage of the high-temperature oxidation reaction of JB100, and the amounts of final products CO2 and H2O are increased. Compared with JB100, JBF shows an enhanced OH group intensity in the combustion flame and a lower soot spectral peak. Furthermore, compared with JB100, under JBF combustion, the pollutant PM2.5 emissions decrease by 13.3 %, PM10 emissions decrease by 13.2 %, PM> 10 particulate matter emissions decrease by 19.3 %, CO emissions decrease by 6.8 %, NOx emissions increase by 21.2 %, and the size of soot particles decreases by 20.8 %.

Preheating and Humidification of the Combustion Air to Increase the Hot Water Boiler Efficiency

Energy efficiency is one of the most pressing topics now. Energy consumption in-creases as living standards rise. Efficient heat production, i.e. efficient use of energy, is achieved with optimal boiler load. The second pressing issue is the protection of the environment from pollution. The process of burning different types of fuels to produce heat or energy results in emissions that can have negative impacts on the environment. One of the solutions to improve air quality is to reduce emissions from heating plants during their production. The scientific paper considers the possibility of a preheating and humidification for combustion air system to increase the efficiency of the boiler and reduce the amount of harmful emissions in flue gases. The boiler efficiency values were calculated before and after the installation of the preheating and humidification system for the combustion air, and measurements of the flue gas analysis were carried out using a Testo 350 flue gas analyzer. Calculations and measurements for flue gas analysis have shown that the combustion air preheating and humidification system increases the boiler house efficiency by 15 % and re-duces nitrogen oxide emissions by 70 %.

Effect of oxidation on the combustion flame characteristics of Jatropha biodiesel

This study investigated the effect of oxidation on the pyrolysis and combustion flame performance of Jatropha biodiesel. To analyze the escape characteristics of multi-component gas products during the pyrolysis and high-temperature oxidation processes of fresh and oxidized Jatropha biodiesel, the TG-FTIR-MS combined system was employed. In addition, various analytical equipment such as an OH-PLIF system, a flue gas analyzer, a spectral analyzer, and a transmission electron microscope were employed to examine the laminar premixed combustion flame and pollutant emissions of Jatropha biodiesel before and after oxidation. The results demonstrate that oxidation exhibits a nonlinear effect on the thermal decomposition of Jatropha biodiesel. Notably, the reaction activation energy exhibits an initial increase and followed by a decrease. Moreover, an increased oxidation degree led to a reduction in the activation energy of the high-temperature oxidation reaction of Jatropha biodiesel, without considerably affecting the total weight loss temperature. Furthermore, the peak temperatures of DTG and DSC exhibited a minor decrease. The production of C2, CH, and OH free radicals in the combustion flame of oxidized Jatropha biodiesel increased, along with an elevation in the spectral intensity of carbon smoke. With an increase in the degree of oxidation, the CO emission concentration from the combustion of Jatropha biodiesel decreased gradually from 75 mg/m3 to 36 mg/m3 after 6 h of oxidation. Additionally, NOx emissions gradually increased from 131 mg/m3 to 186 mg/m3 after 6 h of oxidation, and the particle size of carbon smoke exhibited a reduction of 28%.