Combustion Characteristics Of Anthracite Research Articles

Preheating and combustion characteristics of anthracite under O2/N2, O2/CO2 and O2/CO2/H2O atmospheres

In this study, the anthracite was preheated by a circulating fluidized bed under O2/N2, O2/CO2 and O2/CO2/H2O atmospheres. And the preheating and combustion characteristics of anthracite were studied. Compared with the O2/N2 atmosphere, the structural characteristics of preheated char was improved more obviously under the O2/CO2 and O2/CO2/H2O atmospheres when the oxygen concentration was 31%, which mainly reflected in the increase of BET surface and the increase of small aromatic rings. HCN was mainly NOx precursor during the preheating under different atmospheres. In addition, a novel comprehensive evaluation of ignition and stable combustion characteristics for preheated fuel was proposed. And the minimum thermal power required for preheated char combustion and the combustion heat of preheated coal gas were main factors affecting on the ignition and stable combustion characteristics. The highest combustion efficiency of anthracite was 98.85% under the O2/N2 atmosphere (the oxygen concentrations of primary gas, secondary gas and tertiary gas were 31.0%, 36.0% and 35.0%), and the lowest NO emission in tail flue gas was 24.24 mg/MJ under the air atmosphere.

Study on the Change Law of Red-Green-Blue Values of Infrared Thermal Image in the Process of Anthracite Oxidation and Spontaneous Combustion

As the coal with the highest degree of coalification, anthracite is usually regarded as a mixture composed of organic and inorganic substances, with the characteristics of polymers and composites. It is very important to study the oxidation and spontaneous combustion characteristics of anthracite for the thermal properties of coal-based polymers and composites. Anthracite exhibits varying oxidation and spontaneous combustion characteristics at various stages of the oxidation and spontaneous combustion process, which cannot be fully demonstrated by the coal temperature alone. As a result, this paper develops an online method for characterizing the RGB values of infrared thermal images. The variation of the RGB value of an infrared thermal image during the oxidation and spontaneous combustion of anthracite was investigated. The findings show that there is a clear relationship between R (red), G (green), B (blue), RGB (red/green/blue) values, and coal temperature during the oxidation and spontaneous combustion of anthracite. The R and the G value curves each have one characteristic peak and two characteristic valleys in the experiment. However, the overall change range of the G value curve is relatively small; the B value curve has two characteristic peaks and one characteristic valley. There are no characteristic peaks and valleys in the RGB value curve, despite the influence of experimental instruments and the experimental environment.

Effect of CO2-O2 oxidizing atmospheres on the combustion characteristics of metallurgical coke and anthracite

As a novel method for blast furnace ironmaking, CO2 is utilized in the hot blast and the pulverized coal carrier gas. In order to clarify the function mechanism of CO2/O2 oxidizing atmospheres on the metallurgical reaction of metallurgical coke and anthracite, the combustion characteristics of anthracite and coke in CO2/O2 atmosphere were obtained by non-isothermal thermogravimetry. The physical and chemical structural characteristics of anthracite and coke were measured systematically by using X-ray diffraction(XRD), X-ray fluorescence spectrometer (XRF), laser particle size analysis, scanning electron microscopy(SEM) and Raman spectroscopy analysis. The results show that when the proportion of CO2 in the reaction gas increases, the ignition performance and comprehensive combustion performance of anthracite and coke decrease, and higher heating rate is not conducive to the reaction. The ignition performance and the comprehensive combustion performance of the samples rank in the order anthracite > coke. The volume model (VM) and unreacted core model(URCM) were used to fit the experimental data, and the reaction kinetic parameters and combustion reaction mechanism were obtained. The performance of VM model is slightly better than URCM model.

Effect of Cu(NO3)2 and Cu(CH3COO)2 Activating Additives on Combustion Characteristics of Anthracite and Its Semi-Coke

The process of anthracite and its semi-coke combustion in the presence of 5 wt.% (in terms of dry salt) additives of copper salts Cu(NO3)2 and Cu(CH3COO)2 was studied. The activating additives were introduced by an incipient wetness procedure. The ignition and combustion parameters for coal samples were examined in the combustion chamber at the heating medium temperatures (Tg) of 600–800 °C. The composition of the gaseous combustion products was controlled using an on-line gas analyzer. The fuel modification with copper salts was found to reduce the ignition delay time on average, along with a drop in the minimum ignition temperature Tmin by 138–277 °C. With an increase in Tg temperature, a significant reduction in the ignition delay time for the anthracite and semi-coke samples (by a factor of 6.7) was observed. The maximum difference in the ignition delay time between the original and modified samples of anthracite (ΔTi = 5.5 s) and semi-coke (ΔTi = 5.4 s) was recorded at a Tg temperature of 600 °C in the case of Cu(CH3COO)2. The emergence of micro-explosions was detected at an early stage of combustion via high-speed video imaging for samples modified by copper acetate. According to the on-line gas analysis data, the addition of copper salts permits one to reduce the volume of CO formed by 40% on average, providing complete oxidation of the fuel to CO2. It was shown that the introduction of additives promoted the reduction in the NOx emissions during the combustion of the anthracite and semi-coke samples.

The combustion characteristics of anthracite and pine sawdust blends

ABSTRACTThe combustion characteristics of anthracite, pine sawdust, and their blends were evaluated using a thermogravimetric analyzer (TGA). Pine sawdust was blended with anthracite in the range of 0–100 wt% to evaluate their combustion behavior. Pine sawdust combustion took place in two steps: between 211 and 385°C the volatiles were released and burned, and at 385–491°C char combustion takes place. In contrast, anthracite was characterized by only one combustion stage at 420–684°C. The anthracite and pine sawdust blends presented three combustion steps, corresponding to the sum of the anthracite and pine sawdust individual stages. In the blends combustion process, the temperature displacement occurred compared to anthracite and pine sawdust. There was only one meeting point, i.e., the ignition temperature, for anthracite (496°C). Ignition temperatures were 212°C for pine sawdust and 496°C for anthracite, 313, 311, and 311°C for 80:20, 70:30, and 60:40 (anthracite-to-pine sawdust mass ratio), respectively. The activation energy of blends combustion was lower compared with that of anthracite combustion. The results obtained can be explained by interaction effects when both anthracite and pine sawdust were blended in the combustion process.

Combustion-Supporting Effect of Common Carbonous Solid Waste on Anthracites

In order to study the combustion characteristics of anthracite with additives, the influence of common carbonous solid waste (CSW) on anthracite is studied by thermogravimetry. The results show that appropriate CSW additives mixed with pulverized coal (PC) at PZH Steel can promote the combustion of PC and increase the burning ratio of anthracite greatly. The greater the additive content, the higher the burning ratio at the same conditions. The dynamics models show that the particle size of CSW additives, oxygen concentration, and the diffusion coefficient of oxygen are all very influential for their combustion characteristics. The heat of CSW combustion is absorbed by coal powder, and it consists of part of the coal powder accumulated heat. Then, accumulated heat is higher than dissipation heat ahead of time, so CSW can support combustion of coal powder effectively.

98/03172 Effect of molten caustic leaching on the combustion characteristics of anthracite

98/03172 Effect of molten caustic leaching on the combustion characteristics of anthracite

97/04861 Effect of molten caustic leaching on the combustion characteristics of anthracite: Lee, S. H. and Shon, E. K. Fuel, 1997, 76, (3), 241–246

97/04861 Effect of molten caustic leaching on the combustion characteristics of anthracite: Lee, S. H. and Shon, E. K. Fuel, 1997, 76, (3), 241–246

Effect of molten caustic leaching on the combustion characteristics of anthracite

Changes in structure and combustion characteristics of anthracite after demineralization using molten caustic leaching (MCL) were investigated. The peak temperature of the treated anthracite during thermogravimetric analysis was lower (by ∼ 150 K) than that of raw coal, so that the combustion region of the treated anthracite became similar to that of bituminous coal (350–600°C). The effect of caustic treatment was so marked for anthracite that the maximum reactivity increased about four times above that of the raw coal, whereas the increase in reactivity of bituminous coal was marginal. Analytical investigation showed that coals experience carbonization during MCL treatment, with disruption of reactive hydrocarbons, and that the micro-defects formed by changes in functional group affect the combustion temperature and reactivity. The effect on surface area and particle size was marginal for the anthracite, but very pronounced for the bituminous coal.

Combustion characteristics of anthracite in a vertical cyclone combustor

Isothermal, gas combustion and coal tests were undertaken in order to characterise a vertical cyclone combustor for burning anthracite. Inert particles (alumina cement) were used during the first two series of tests, in order to characterise chamber temperatures, material collection efficiencies and size distribution of particles. Mixture ratios from 0.4 up to 1.6 were tested in steps of 0.2. Under isothermal conditions, an optimum penetration length of vortex finder into the combustion chamber was found to be approximately 10% of the chamber length. The highest temperature can be obtained in the lower section of the combustion chamber both in gas and in coal combustion. The collection efficiency of the cyclone combustor in the various modes of operation was found to be excellent. For coal tests, mixed firing with coal and gas was adopted to sustain the flame in the combustor. The mixed fuels investigated here contain 60, 70 and 80% by mass of coal, and the 70% case was found favorable in the context of carbon burnout and collection efficiency.