Combustion CO2 Research Articles

Enhancing catalytic performance of Ag-CeO2 catalysts for catalytic CO combustion: Ag-CeO2 interface interaction and Na-promoting action

Ag-CeO2 catalysts were prepared via urea- and activated carbon- assisted pyrolysis to study an improvement strategy for their catalytic performance in catalytic CO combustion. Different synthetic methods induced the change of Ag-CeO2 interface interaction by tuning the surface chemical state of Ag nanoparticles and CeO2 nanoparticles. However, it was completely different to arouse the change degree in the structure and performance of these Ag-CeO2 catalysts. Fabrication of Ag-CeO2 catalysts using a urea pyrolysis induced to create an Ag-CeO2 interface with more metallic Ag species, which improved the reductivity of CeO2 surface and enhanced the Ag-CeO2 catalyst performance. Fabrication of Ag-CeO2 catalysts using an activated carbon pyrolysis method induced to form an Ag-CeO2 interface with more positively charged Ag+ ions and required higher temperature of CO conversion. For the Ag-CeO2 catalysts with more positively charged Ag+ species, the participation of sodium salts could alleviate Ag nanoparticle oxidation and promoted the transformation of Ag-CeO2 interface with more positively charged Ag+ ions into Ag-CeO2 interface with more metallic Ag species, which caused the formation of more Ce3+ cations and the production of more reducible surface oxygen and enhanced the catalyst performance in catalytic CO combustion.

Effects of hydrogen assisted combustion of EBNOL IN SI engines under variable compression ratio and ignition timing

Alcohols are oxygenated fuels, holding a good reputation among alternatives, but single alcohol does not possess all qualities. Besides, the high latent heat and low vapor pressure limit their uses in SI engines. Hence, an energy enhancing and combustion promoting fuel helps overcome the drawbacks, among all available hydrogen fits the race most. Hence, hydrogen-assisted combustion of equivolume blend of ethanol/butanol (ENBOL) is experimentally tested under various compression ratios (CR) (11–15), ignition timing (16°CA-24°CA BTDC) for three hydrogen fractions (5%–15%) at three speeds (1400RPM-1800RPM). The experimental outcome notices an increase in brake power (BP), brake thermal efficiency (BTE), peak pressure (Pmax), heat release rate (HRRmax), and NOx emissions with increasing CR and Hydrogen addition. The combustion duration, CO, and UBHC emissions reduce while CO2 emissions reduce with hydrogen; increasing CR notices a drop in CO2 at a much advanced or much-delayed ignition. Hydrogen improves combustion but reduces volumetric efficiency; increasing CR improves it, and hydrogen effect reduces with increasing CR. BP, BTE, and CA10-90 improve with retarding ignition from 24°CA, while CA10, Pmax, and HRRmax reduce continuously. UBHC and CO emissions increase while NOx reduces with retarding ignition. The ignition timing of 20°CA at CR15 and 15% hydrogen performed better than gasoline.

Effects of high-speed spin on the reacting flow of drag reduction equipment under rapid depressurization

• The coupled combustion of two gases under dual environmental stress was simulated. • The effects of spin on the reaction flow under depressurization were analyzed. • A vortex core forms with a high tangential velocity gradient in the spin case. • Mass addition is a primary factor for the spin to improve the device performance. The drag reduction equipment (DRE) suffers dual environmental stress of high-speed spin and rapid depressurization during the launching process, disturbing the projectile intensely. To research the effect of this extreme process on heat and mass transfer, flow field development, as well as drag reduction performance of the DRE, a numerical model was established based on the MT-based pyrotechnics combustion mechanism and the H 2 -CO combustion mechanism. Simulation on the unsteady reacting flow was conducted to investigate the effect of high-speed spin on the performance of the DRE under depressurization. The results indicate that the wake flow field of the DRE transforms from a supersonic under-expanded jet into a subsonic swirling flow, and two recirculation zones with low-pressure appear at the base of the DRE. The transition region between propellant gas and igniter gas in the combustion chamber displays the Kelvin-Helmholtz instability, in which a vortex core forms with a high tangential velocity gradient. The igniter gas burns in the combustion chamber, resulting in an axial high-temperature region. And then the combustion products of igniter gas are mixed with propellant gas and inject outwards, reacting with the air near the jet boundary to be an intense post-combustion. High-speed spin improves the nozzle mass flow rate, enhancing the post-combustion. Eventually, compared with the non-spin case, the mass flow rate and base temperature in the case of 20,000 rpm are improved by 67.6% and 21.56%, respectively. And the base drag is reduced by 10.14%.

Features of exhaust gases afterburning in a converter when using two-tier oxygen lances for refining

The theoretical substantiation was carried out for increasing the efficiency of converter gases afterburning in the unit with a two­tier supply of multi­pulse oxygen jets and combustion of CO to CO2 in the channel flow of gases leaving the reaction zone. The authors made the thermodynamic analysis of the process of exhaust gases afterburning in converter cavity when using two­tier oxygen lances for refining. It is shown that when oxygen gas jets are blown through the upper­tier nozzles with a flow rate of 10 – 40 % of the total minute flow rate, a sufficiently complete afterburning of carbon monoxide CO is not provided. The limiting factors are the uneven amount and disorganized output of the CO formed in the reaction zones during various operation periods, low efficiency of mixing the waste stream with high­speed gas jets and an excessively excessive amount of oxygen supplied for afterburning, insufficient mixing of the components of the gas phase and low reaction rate. It is shown that when the conditions are provided for CO afterburning to the concentration ratio in the gas phase, temperature of the exhaust gas in the converter cavity can increase from 1800 to 2000 K, then the thermal effect of the exothermic reaction decreases. The amount of oxygen injected for CO afterburning must correspond to the residual carbon content in the metal at m3/min ≈ 100 [Сост ] %. Excess of oxygen in the gas phase and presence of a significant amount of neutral gas significantly reduce the utilization rate of the generated heat in the unit.

Self-Sustained Catalytic Combustion of Co Enhanced by Micro Fluidized Bed: Stability Operation, Fluidization State and Cfd Simulation

Self-Sustained Catalytic Combustion of Co Enhanced by Micro Fluidized Bed: Stability Operation, Fluidization State and Cfd Simulation

РОЗВИТОК КОНЦЕПЦІЇ ПІДВИЩЕННЯ ЕНЕРГОЕФЕКТИВНОСТІ ДУГОВОЇ СТАЛЕПЛАВИЛЬНОЇ ПЕЧІ ШЛЯХОМ УТИЛІЗАЦІЇ ТЕПЛОТИ ДИМОВИХ ГАЗІВ ДЛЯ ПОПЕРЕДНЬОГО НАГРІВУ СКРАПУ

An important factor in improving the energy efficiency of the electric arc steelmaking furnace (EAF) is utilization of the flue gas energy to preheat the initial charge. Implementation of the process in existing EAF requires the measures to synchronize with the carbon monoxide post combustion and to prevent of the toxic PCDD/F formation when conventional scrap heating, which is significantly complicated in a traditional scheme of CO afterburning with a single-stage air inflow through a temperature and concentration factors. The technological basics of medium-temperature scrap preheating by EAF flue gas have been developed and substantiated. Numerical study of carbon monoxide burning thermodynamics and kinetics shown that implementation of two-stage inflow of air into postcombustion chamber for stoichiometric combustion of CO and cooling the heat carrier provides a comprehensive solution of mentioned problems. The ratio of primary and secondary flows 1 to 3.5 provides allowable concentration of carbon monoxide in the ducts; obtaining gas mixture with a temperature of up to 500 °C, which prevents PCDD/F formation; acceptable temperature operating conditions of bag fabric filters of the gas cleaning system within 100 °C regardless of scrap preheating. Numerical simulation of the heat exchange process between the charge layer and the gaseous heat carrier reveal that shredder scrap of standard bulk density 0.9 t/m3 and mass of half EAF capacity can be preheated up to temperature of 450 °C in 18-20 minutes. Given value corresponds to the duration of technological period in the EAF heat cycle, characterizing by comparatively stable emission and maximal temperature of the flue gas flow. Reduction of the scrap fragments bulk density and the average size, as well as increasing the ratio of the heating chamber height to its diameter in the range from 0.7 to 2.0, promotes the heating rate magnification. The technology provides specific energy savings within 20-30 kW.h per ton of steel and can be implemented in existing electric steelmaking shop of the mini-mill without additional CO2 emissions. The payback period for a 50-ton EAF with annual productivity of 400-450 thousand tons of steel is 14-18 months.

Numerical Study of Large-Scale Fire in Makkah’s King Abdulaziz Road Tunnel

Tunnel fires are one of the most dangerous catastrophic events that endanger human life. They cause damage to infrastructure because of the limited space in the tunnel, lack of escape facilities, and difficulty that intervention forces have in reaching the fire position, especially in highly crowded areas, such as Makkah in the Hajj season. Unfortunately, performing experimental tests on tunnel fire safety is particularly challenging because of the prohibitive cost, limited possibilities, and losses that these tests can cause. Therefore, large-scale modeling, using fire dynamic simulation, is one of the best techniques used to limit these costs and losses. In the present work, a fire scenario in the Makkah’s King Abdulaziz Road tunnel was analyzed using the Fire Dynamics Simulator (FDS). The effects of the heat released per unit area, soot yield, and CO yield on the gas temperature, radiation, concentrations of the oxygen and combustion products CO and CO2, and air velocity were examined. The results showed that the radiation increased with the heat released per unit area and the soot yield affected all parameters, except the oxygen concentration and air velocity. The CO yield significantly affects CO concentration, and its influence on the other studied parameters is negligible. Moreover, based on the validation part, the results proved that FDS have limitations in tunnel fires, which impact the smoke layer calculation at the upstream zone of the fire. Therefore, the users or researchers should carefully be concerned about these weaknesses when using FDS to simulate tunnel fires. Further comprehensive research is crucial, as tunnel fires have severe impacts on various aspects of people’s lives.

Analysis of the Physicochemical Characteristics of Biochar Obtained by Slow Pyrolysis of Nut Shells in a Nitrogen Atmosphere

The process of slow pyrolysis of seven nut shell samples, in a nitrogen-purged atmosphere, has been studied, as well as characteristics of biochar obtained. The heat carrier with a temperature of 400–600 °C (with a step of 100 °C) was supplied indirectly using a double-walled reactor. The heating rate was 60 °C/min. At increased temperature of the heating medium, a decrease in the amount of the resulting carbon residue averaged 6.2 wt%. The release of non-condensable combustible gas-phase compounds CO, CH4, and H2, with maximum concentrations of 12.7, 14.0, and 0.7 vol%, respectively, was registered. The features of the obtained biochar sample conversions were studied using thermal analysis in inert (nitrogen) and oxidative (air) mediums at 10 °C/min heating rate. Kinetic analysis was performed using Coats–Redfern method. Thermal analysis showed that the main weight loss (Δm = 32.8–43.0 wt%) occurs at temperatures ranging between 290 °C and 400 °C, which is due to cellulose decomposition. The maximum carbon content and, hence, heat value were obtained for biochars made from macadamia nut and walnut shells. An increased degree of coalification of the biochar samples affected their reactivity and, in particular, caused an increase in the initial temperature of intense oxidation (on average, by 73 °C). While technical and elemental composition of nut shell samples studied were quite similar, the morphology of obtained biochar was different. The morphology of particles was also observed to change as the heating medium temperature increased, which was expressed in the increased inhomogeneity of particle surface. The activation energy values, for biochar conversion in an inert medium, were found to vary in the range of 10–35 kJ/mol and, in an oxidative medium—50–80 kJ/mol. According to literature data, these values were characteristic for lignin fibers decomposition and oxidation, respectively.

Life cycle assessment of the co-combustion system of single-use plastic waste and lignite coal to promote circular economy

Single-use plastics waste is a thermosetting-thermoplastic polymer generated specifically from packaging industries. Incineration, landfilling, combustion, open discharge in liquids fail its effective disposal. Co-combustion via co-processing is a novel technique for disposal. In this study, investigative thermogravimetric analysis of the co-combustion of lignite coal (AL) and single-use plastic waste (PW) in the blend ratios of 50:50, 60:40, 70:30 was carried out under non-isothermal conditions to promote co-combustion via co-processing technique for environment-friendly disposal. Thermal degradation behavioral study was carried out at higher blending ratios of 30–50%. The effect of the mass ratio of PW to AL on co-combustion characteristics was analyzed. The Freeman-Carroll, Sharp-Wentworth methods derived energy of activation for the process of co-combustion in the limits of 65–155 kJ/mol, 44–75 kJ/mol. Volume Contracting and Diffusional Reaction 2D solid-state reaction mechanisms were followed by the co-combustion system as derived by Coats-Redfern and Kennedy-Clark methods. Master plot method validated the same results. The co-combustion performance was evaluated using co-combustion (CSI), ignition (IG), burnout (IB) indices. The highest CSI value was reported for the 60:40 blend. Burnout temperature (Tb) decreased with an increase in blending ratio and suggested an effective co-combustion process. Blend (70:30) reported the highest interaction in blends and confirmed the synergistic effect. The principal component analysis described the co-combustion process as three stages (100–200, 265–425, 425–700) oC with specific materials. The co-combustion process was optimized using the methodology of surface response and validated using neural network models (NNM 4,5) for the effect of temperature and blend ratio on mass loss. The characterization study confirmed the presence of minerals alumino-silicates, dimorphs pyrite, marcasite, gypsum, barite, hydrated sulfates, calcite, siderite, and functional groups –OH, -CH2, -Si-O responsible for autocatalytic reactions. Life cycle assessment confirmed the sustainability of the co-combustion process of lignite and plastic waste. The present study benefits for scale-up, optimization, waste to energy conversion, pollution reduction, and environmentally friendly disposal via the co-combustion process.

Video registration of physicochemical processes in BOF cavity at bath top blowing at application oxygen lances of various designs. Report 3. The picture of bath blowing at application two-level oxygen lances

Further increase of resources- and energy-saving efficiency of BOF processes is unthinkable without development of new methods of blowing and designs of blowing devices. It requires information on the real physicochemical phenomena in the converter cavity accompanying the blowing of the converter bath using new designs of oxygen lances in order to assess the possible risks in the mastering of the proposed developments in industrial conditions. The paper presents the results of video filming of the top blowing of a 80-kg converter bath by groups of multi-pulse supersonic and sonic oxygen jets formed, respectively, by Laval and cylindrical two-level nozzles of two designs equipped with double-row tips with a circular arrangement of Laval nozzles and cylindrical ones and upper block with cylindrical nozzles. Previously unknown information was obtained on the picture of the bath blowing with the formation of a reaction zone of interaction of supersonic and sonic oxygen jets with a metal melt with a flow of carbon monoxide going out the bath and afterburning of CO to CO2 under conditions of a counter-directed double curtain of sonic oxygen jets at different levels of location of the foamed slag-metal emulsions. It was established that in the initial period of blowing during slag formation most of the thermal energy of CO to CO2 combustion flares is transferred to the surface of the bath with lumps of added lime, and the rest is transferred by forced convection to the converter walls and gases escaping from the bath to the neck. In the case of the location of the foamed slag level at the upper tier of the cylindrical nozzles of the lance, heat transfer from high-temperature flares of localized afterburning of CO to CO2 within a limited in size near-lance flow of exhaust gases from the reaction zone is carried out according to the laws of submerged combustion and is completed completely in foamed slag-metal emulsion with the prevention of aggressive action of afterburning flares and volumes of overheated slag on the converter lining. Revealed and recorded by video recording modes of blowing the converter bath, contributing to the development of such undesirable phenomena during smelting as the appearance of intense emissions of slag-metal suspension from the facility, coagulation of the slag with the cessation of dephosphorization of the metal melt, the development of intense dust formation and the removal of small metal particles and slag with the formation of crust on the lance barrel. A variant of the final stage of blowing with a transition to supplying nitrogen instead of oxygen through cylindrical nozzles of two-level lances was experimentally tested, which provides an effective reduction in the level of foamed slag-metal emulsion before the converter turning down. The data obtained were used in the development of an industrial design of a two-level lance with a double-row tip, blowing and slag modes of blowing a converter bath with its use.

Investigation on the catalytic combustion of CO over LaMn1‐xCuxO3 promoted by acid treatment

AbstractThere are large amounts of CO pollutants in the off‐gas of the iron and steel industry, which cause serious harm to the environment and human health. To control the emission of CO more effectively, in this paper, LaMn1‐xCuxO3 (x = 0, 0.25) perovskite catalysts were prepared and then modified by dilute nitric acid. And the physicochemical properties and the catalytic activity of perovskite were investigated and analyzed. The activity results indicate that the Cu2+ substitution and acid treatment could obviously promote the catalytic activity of catalysts for CO oxidation. Among the prepared samples, LaMn0.75Cu0.25O3‐H exhibits the highest activity with 90% CO conversion at 176.5°C, and the self‐sustained combustion of CO is successfully achieved. And the long‐time stability test shows that LaMn0.75Cu0.25O3‐H can keep 100% CO conversion, and the activity remains almost unchanged. Combined with the x‐ray photoelectron spectroscopy (XPS) and H2 temperature‐programmed reduction (H2‐TPR) results, the increased activity of LaMn0.75Cu0.25O3‐H catalyst is mainly ascribed to the high concentration of Mn4+ and abundant oxygen vacancies. On the other hand, the morphology of perovskite catalysts was remolded by acid etching, and the formation of the porous structure significantly increases the specific surface area. The above results show that the substitution of Cu and acid treatment for perovskite catalysts is a feasible strategy to improve CO catalytic combustion activity.

Stabilization of Pt in SiO2–Al2O3 Microspheres at High Mechanical Resistance, Promoted with W Oxides for the Combustion of CO

This study shows the development of a combustion promoter for the oil-refining process called fluid catalytic cracking (FCC). The investigation of a catalyst prepared for the combustion of CO composed of 0.05 wt% Pt supported on SiO2–Al2O3–0.5 wt% W microspheres with high mechanical resistance, promoted with tungsten oxides (WOx) that can inhibit the sintering of Pt, is reported. The addition of WOx in SiO2–Al2O3 inhibited the decrease in the specific area when calcined from 550 °C to 950 °C. SiO2–Al2O3 support in the form of calcined microspheres with average diameters between 70–105 µm were produced by spray drying, using two atomization discs with vanes of different geometry: a straight rectangular blade disc (DAR) and a curved rectangular vanes disc (DAC). The DAR disk produced whole microspheres, while the DAC had hollow and broken microspheres. The microspheres were characterized by XRD, SEM, optical microscopy, N2 physisorption (BET area) and fracture resistance tests. The Pt catalysts were evaluated by TPR, H2 chemisorption and CO combustion. The catalyst of 0.05 wt% Pt/SiO2–Al2O3–0.5 wt% turned out to be the most stable. A thermal stabilization effect was observed at contents lower than 1 wt% W that allowed it to inhibit the sintering of the Pt catalyst.

Deep Insight into the Mechanism of Catalytic Combustion of CO and CH4 over SrTi1-xBxO3 (B = Co, Fe, Mn, Ni, and Cu) Perovskite via Flame Spray Pyrolysis.

Perovskites have been recognized as affordable substitutes for noble-metal catalysts for their tunable catalytic activity and thermal stability. Nevertheless, the highly demanding synthesis procedure still hinders the application of perovskites in catalytic combustion. In this work, a series of nanostructured SiTiO3 perovskites with B-site partial substitution by Co, Fe, Mn, Ni, and Cu are synthesized via flame spray pyrolysis in one step. The comprehensive characterizations on textural properties of nanostructured perovskites reveal that the flame-made perovskite nanoparticles all exhibit high crystal purity and large specific surface area (∼40 m2/g). Furthermore, the highest catalytic activity is achieved by SrTi0.5Co0.5O3 due to the formation of favorable oxygen vacancies, outstanding reducibility, and oxygen desorption capability. Additionally, the presence of 10 vol % water vapor during long-term testing indicates remarkable durability and water resistance. Finally, the CO oxidation and CH4 dehydrogenation on SrTiO3 incorporating Co atoms are more thermodynamically and kinetically favorable than those on other doped surfaces.

CuO Quantum Dots Supported by SrTiO3 Perovskite Using the Flame Spray Pyrolysis Method: Enhanced Activity and Excellent Thermal Resistance for Catalytic Combustion of CO and CH4.

As a non-noble-metal catalyst, CuO has great potential in the catalytic combustion of CO and CH4. In this work, the influence of loading active copper components onto perovskites and essential operating parameters in flame aerosol synthesis has been experimentally and theoretically investigated to optimize the catalytic efficiency for the complete oxidation of lean CO and CH4. Herein, the CuO-SrTiO3 nanocatalysts are one-step-synthesized by flame spray pyrolysis with varied copper loadings and precursor feeding rates. The sample under the precursor flow rate of 3 mL/min and the CuO loading of 15 mol % demonstrates optimal catalytic performance. It is primarily attributed to the excellent low-temperature reducibility and improved activity of copper species originated by CuO quantum dots and metal-support interaction. Besides, SrTiO3 perovskite as a support can effectively inhibit the sintering of CuO quantum dots at high temperatures, which is responsible for the excellent sintering and water deactivation resistances.

Improving the tests of catalytic converters accounting for the relationship between the composition of the working mixture entering the engine combustion chamber and CO and CH in exhaust gases

The article presents results of the study aimed to establish the relationship between the working mixture entering the engine combustion chamber and CO and CH in the exhaust gases. On the basis of the theory of fuel combustion in the engine chamber and the systematic approach, and using the mathematical methods, the fuel combustion in the combustion chamber is analyzed at low ambient temperatures to decrease emissions of carbon monoxide and hydrocarbons. The criterion for optimizing the tests of catalytic converters is substantiated for low temperatures - temperatures of the heat flow of the mixture at the exit from the combustion chambers of the engine cylinder. The limitation is the warm-up time of the catalytic converter when testing it on vehicles operating at low temperatures and the standards for the content of CO and CH in the exhaust gases of a passenger car engine. The application of the methods and the mathematical model can be the basis for supplementing UNECE Regulation No. 83-06 and improving the VI type test method for vehicles operating at low ambient temperatures.

Ilmenite as alternative bed material for the combustion of coal and biomass blends in a fluidised bed combustor to improve combustion performance and reduce agglomeration tendency

Co-firing coal and biomass has the potential to reduce GHG emissions. However, high levels of alkali and alkaline metals in biomass ash can bring additional issues to the operation of coal-fired boilers. This study investigates the effects of ilmenite as the bed material on CO and NOx emissions and combustion efficiency of a coal and biomass blend, and the agglomeration tendency of the bed material with a pilot-scale (30 kWth) bubbling fluidised bed combustor. The experiments were carried out at 900 °C using a bituminous coal blended with wheat straw pellets at 40 wt% as the fuel and silica sand as the baseline bed material. Samples of agglomerates collected from the combustor and cyclone ash were characterised by SEM-EDS, XRD, and XRF. The results revealed that ilmenite could reduce the level of excess air required to achieve complete combustion due to lower CO emissions and less efficiency loss compared to silica sand. However, ilmenite increased NOx emissions. Furthermore, the characterisation of the obtained agglomerates and cyclone ash showed that ilmenite could hinder the K-rich molten substance attachment to the bed material, leading to significantly smaller agglomerates and hence less tendency towards defluidisation in comparison to silica sand.

Influence of partial components removal on pyrolysis behavior of lignocellulosic biowaste in molten salts

Using molten NaNO3–KNO3–NaNO2 for biowaste pyrolysis provides a promising way to synergize the utilization of biowaste and fluctuating solar energy. However, the diversity of lignocellulosic biowaste and violent decomposition complicated the interactions between natural constituents. In this study, the pyrolysis behavior of woody and agricultural herbaceous lignocellulosic biowaste in molten salts was comprehensively investigated at 300 °C. Through the selective removal of partial hemicellulose or lignin, the specific role of the original structure on the products formation characteristics was further estimated. The results showed that more volatiles were released from the hemicellulose-enriched agricultural herbaceous biowaste than cellulose-enriched woody biowaste. The yields of water and organic liquids from hemicellulose or lignin removal were higher than that of raw biowaste. Specifically, hemicellulose dominated the generation of nitrogenous substances in the liquid products. As for the gas product, its yield from the hemicellulose removal sample was higher than raw biowaste but it decreased after removing lignin. Lignin was the primary contributor to the combustible CO, H2, and CH4, while the production of CO2 was more affected by hemicellulose. The lignin would compete with hemicellulose and be superior to the latter in the reaction with molten salt.

New technology for producing high-quality combustible gas by high-temperature reaction of dust-removal coke powder in mixed atmosphere

Converter high-temperature flue gas (CHFG) is an important energy source, but it contains a low concentration of combustible gas and its use produces significant CO2 emissions. We propose a method for increasing the combustible gas concentration of CHFG, which involves injecting dust-removal coke powder (DRCP) into CHFG and catalyzing their reaction with metal oxide. The presented technology not only converts CO2 into combustible gas CO but also provides a new direction for efficient and clean utilization of DRCP. It is theoretically based on thermodynamic calculations (FactSage 6.1) and thermal analysis experiments, and its feasibility is verified through dropper furnace (DF) and industrial experiments. The phase composition is characterized by scanning electron microscopy coupled with energy-dispersive X-ray analysis, X-ray diffraction, and X-ray fluorescence. The results show that the initial decomposition temperature, the maximum decomposition temperature, and the final decomposition temperature of the DRCP gasification reaction are all reduced after adding metal oxide. The CO, H2, and CH4 contents in the high-temperature flue gas increase, whereas the CO2 content decreases. In addition, the reduction products with the addition of CaO are mainly CaO and a small amount of CaCO3. However, the reduction products when Fe2O3 and FeO are added mainly include Fe and Fe3C. Simultaneously, the addition of metal oxide can increase the gasification reactivity of DRCP. After the DRCP is injected, the combustible gas concentration and recovery time are obviously improved. The feasibility of the proposed technology is systematically verified through a series of experiments. This technology provides an innovative solution for converting industrial waste gas into valuable resources using industrial solid waste.

Analysis of the Impact of Physicochemical Parameters Characterizing Coal Mine Waste on the Initialization of Self-Ignition Process with Application of Cluster Analysis

Purpose The subject of the research presented in this paper is the analysis of physicochemical parameters characterizing coal mine waste, in terms of their impact on the initialization of the self-ignition phenomenon. Methods The model was constructed with the application of Hierarchical Cluster Analysis complemented with a colour data map enabling the tracing of similarities between the samples of coal mine waste in the space of parameters and between the examined physicochemical parameters in the space of samples. The data set analysed included parameters characterizing coal mine waste collected from 12 various coal mine waste dumps, either in operation or closed, and where thermal effects either took place or were not reported. Results The HCA model constructed and complemented with a colour data map revealed that the tendency of coal mine waste to self-ignite is primarily affected by the contents of moisture, ash, volatile matter, C and S, values of heat of combustion, calorific value and contents of SiO2, Al2O3, K2O, SO3, TiO2, Co, Ni and Rb. Practical implications One of the major environmental hazards associated with the storage of coal mine waste is the possibility of self-ignition. At present, there are no applicable methods of assessment of this risk. The application of Hierarchical Clustering Analysis complemented with a colour data map enabled the analysis of data structures organized in matrix X(m × n) by tracing the similarities between the examined objects in the parameter space and between the measured parameters in the object space, and therefore contributed to the development of procedures of coal mine waste self-ignition risk assessment. Originality/value The originality of the study presented in this paper comes from finding the parameters affecting the tendency of coal mine waste to self-ignite.

Analysis of the Impact of Physicochemical Parameters Characterizing Coal Mine Waste on the Initialization of Self-Ignition Process with Application of Cluster Analysis

Purpose The subject of the research presented in this paper is the analysis of physicochemical parameters characterizing coal mine waste, in terms of their impact on the initialization of the self-ignition phenomenon. Methods The model was constructed with the application of Hierarchical Cluster Analysis complemented with a colour data map enabling the tracing of similarities between the samples of coal mine waste in the space of parameters and between the examined physicochemical parameters in the space of samples. The data set analysed included parameters characterizing coal mine waste collected from 12 various coal mine waste dumps, either in operation or closed, and where thermal effects either took place or were not reported. Results The HCA model constructed and complemented with a colour data map revealed that the tendency of coal mine waste to self-ignite is primarily affected by the contents of moisture, ash, volatile matter, C and S, values of heat of combustion, calorific value and contents of SiO2, Al2O3, K2O, SO3, TiO2, Co, Ni and Rb. Practical implications One of the major environmental hazards associated with the storage of coal mine waste is the possibility of self-ignition. At present, there are no applicable methods of assessment of this risk. The application of Hierarchical Clustering Analysis complemented with a colour data map enabled the analysis of data structures organized in matrix X(m × n) by tracing the similarities between the examined objects in the parameter space and between the measured parameters in the object space, and therefore contributed to the development of procedures of coal mine waste self-ignition risk assessment. Originality/value The originality of the study presented in this paper comes from finding the parameters affecting the tendency of coal mine waste to self-ignite.