Combustion Of Brown Coal Research Articles

THE MULTIFACTORIAL ASSESSMENT OF CARCINOGENIC EFFECTS OF ENVIRONMENTAL FACTORS

Objective: Assessment of effects of environmental factors on development of lung cancer. Methods: We applied a multiple factor approach to designing the epidemiologic study. The object of our research was the town of Karpinsk, the Sverdlovsk Region, situated within the environmental radiochemical area with a high radon potential characterized by a moderate level of contamination of the natural environment and high cancer incidence rates among the local population. The case group included 142 lung cancer patients and the control group consisted of 220 people without cancer. We analyzed health effects of 12 biological, social, occupational, and environmental factors. We used the deterministic algorithms of pattern recognition for the multifactor data processing. Results: We have established the power and nature of the effect of each factor under study on development of lung cancer. Using mathematical modeling, we assessed efficiency of hypothetical scenarios of some risk factors correction. Conclusions: Among the lung cancer environmental risk factors in Karpinsk, indoor air pollution with carcinogenic brown coal combustion products was of great importance; the contribution of indoor exposure to radon isotopes was low (0.9 %).

Pilot-scale experimental and CFD modeling investigations of oxy-fuel combustion of Victorian brown coal

This paper presents the first trial in the world for experimental and modeling investigation of oxy-fuel combustion of Victorian brown coal in a 3MWth pilot-scale facility. Two coal samples with different moisture contents, wet (40wt% moisture) and air-dried (24wt% moisture), were tested in air- and oxy-firing modes with oxygen level varying from 27% (vol) to 40% in furnace. The commercial software, FLUENT 13, was employed to interpret the experimental data by taking into account a series of validated refined sub-models for oxy-fuel combustion. The modeling results showed reasonable agreement with the measurements of flue gas temperature profile as well as in-situ flame photographs in furnace. As has been confirmed, a rather identical flue gas temperature profile was achieved between air-firing and oxy-27% O2 for the dried Victorian brown coal. For the wet brown coal with 42wt% moisture, 30% O2 in oxy-fuel mode is however essential to match air to achieve an identical flue gas temperature profile. Even so, under above optimum retrofit conditions, the radiative heat transfer and CO emission profiles were still slightly mismatched between air-firing and oxy-firing cases regardless of the moisture content within coal. The radiative heat transfer was increased in wet coal oxy-firing because of the higher gas emissivity for the abundant CO2 and H2O within the flue gas. The CO emission concentration in oxy-fuel mode was raised, due to the enhanced C–CO2 and C–H2O gasification reactions that occurred readily at relatively low temperatures for Victorian brown coal char. The presence of no less than 30% oxygen in primary gas is also essential to minimise particle ignition delay caused by the large specific heat capacity of CO2 and steam. For flue gas properties, it has been confirmed that, under the optimised oxy-fuel conditions, the typical CO2 purity reached approximately 80% in dried flue gas, in which the excess oxygen remained at ∼4% whereas steam reached 35%, relative to 10% in air-firing flue gas. By shifting coal combustion from air-firing to oxy-fuel mode, the flue gas recirculation ratio varied from 48% to 64% for the use of wet and dried coals, which are considerably lower than the literature results for bituminous coal.

Adsorption Kinetics of Reactive Dyes on Ash from Town Heating Plant

Abstract In order to investigate the mechanism of adsorption of reactive dyes from the textile industry on ash from heating plant produced by brown coal combustion, some characteristic sorption constants are determined using Langergren adsorption equations for pseudo-fi rst and pseudo-second order. Combined kinetic models of pseudo-first order and pseudo-second order can provide a simple but satisfactory explanation of the adsorption process for a reactive dye. According to the characteristic diagrams and results of adsorption kinetic parameters of reactive dyes on ashes, for the applied amounts of the adsorbents and different initial dye concentrations, it can be concluded that the rate of sorption is fully functionally described by second order adsorption model. According to the results, the rate constant of pseudo-second order decreases with increasing initial dye concentration and increases with increasing amount of adsorbent – ash.

Nitrogen oxides, sulfur trioxide, and mercury emissions during oxy-fuel fluidized bed combustion of Victorian brown coal.

This study investigates, for the first time, the NOx, N2O, SO3, and Hg emissions from combustion of a Victorian brown coal in a 10 kWth fluidized bed unit under oxy-fuel combustion conditions. Compared to air combustion, lower NOx emissions and higher N2O formation were observed in the oxy-fuel atmosphere. These NOx reduction and N2O formations were further enhanced with steam in the combustion environment. The NOx concentration level in the flue gas was within the permissible limit in coal-fired power plants in Victoria. Therefore, an additional NOx removal system will not be required using this coal. In contrast, both SO3 and gaseous mercury concentrations were considerably higher under oxy-fuel combustion compared to that in the air combustion. Around 83% of total gaseous mercury released was Hg(0), with the rest emitted as Hg(2+). Therefore, to control harmful Hg(0), a mercury removal system may need to be considered to avoid corrosion in the boiler and CO2 separation units during the oxy-fuel fluidized-bed combustion using this coal.

Cu recovery from industrial wastewater using brown coal

The etching process by copper chloride is widely used in printed wiring board manufacturing. Brown coal has an ion exchange ability because it has carboxy groups and hydroxyl groups in it. Using this ability of brown coal, the copper recovery from the waste etching solution by low energy consumption method is studied. Copper ion in the waste solution can be loaded on Loy Yang brown coal around 8.5wt.% by adding ammonium hydroxide, adjusting pH to 9–11.5 and stirring the solution at room temperature. Cu-loaded brown coal can be burnt at extremely low temperature; 160–180°C, and 0.5–1.0μm copper oxide particles are formed as the residue. In order to commercialize the copper recovery system, since Cu-loading amount and low temperature combustion of Cu-loaded brown coal are key factors of this process cost, Cu-loading conditions and the reaction kinetics of low temperature combustion of Cu-loaded brown coal by TG analysis are studied. By the kinetic analysis using TG data, activation energy of initial combustion is affected by Cu-loading amount. When Cu-loading is 8.6wt.%, it is estimated that the activation energy is reduced to 56% of that of the raw coal.

Molecular dynamic simulation of spontaneous combustion and pyrolysis of brown coal using ReaxFF

Brown coal is a soft sedimentary organic rock which is complex in nature and is the main source of energy production. In this work, we have studied the combustion and pyrolysis of brown coal using reactive molecular dynamic (MD) simulation. To make the large scale (above 1000 of atoms) reactive system practical, ReaxFF MD system was used which is 100 times faster than the methods of quantum mechanics (QM). To examine the pyrolysis/combustion process and initiation mechanism of brown coal, a fuel lean (ϕ=2), fuel rich (ϕ=0.5) and stoichiometric (ϕ=1) conditions were used in this work. The temperature used was high as per experimental reported condition so as to enable chemical reaction within a computationally affordable time. It was observed that the combustion of brown coal was initialized by thermal degradation subsequently forming small fragments. As the brown coal molecule oxidizes or thermally decomposes, hydrogen is abstracted and reacts with oxygen to form large amount of H2O molecules. Furthermore, the combustion of coal was also studied in the same conditions namely fuel rich, fuel lean and stoichiometric. Potential energy gradually decreases at high temperature while it was the reverse in pyrolysis. It was found that the effects of densities are lesser as compared to temperature. Some important intermediate like formaldehyde (HCHO) generated during the simulation reaction agreed well with the experimental data reported in literature.

Calorimetry in testing waste materials from the brown coal combustion

The calorimetric measurements were applied in testing the wastes collected from different furnaces in electric power plants as materials to be used in civil engineering. The fly ash materials were collected from two power stations based on different brown coal deposits and working with conventional and fluidized bed installation. The reactivity of high calcium fly ash from sub-bituminous coal combustion has been proved in calorimetric, conductometric, chemical shrinkage, and rheological measurements before their practical implementation on larger scale. Highly soluble components of fly ash contribute to the hydration products and structure formation, followed by setting and hardening of fly ash–cement mixture. These results have been the base of research project aimed in the innovative solutions dealing with the management of deposits of wastes generated as a result of coal combustion. The standardization and potential use on larger scale of these materials, necessary from the environmental point of view, seems to be the question of nearest future.

Use of synthetic oxygen carriers for Chemical Looping Combustion of Victorian brown coal

Chemical Looping Combustion (CLC) is a promising alternative technology for inherent capture of CO2 at a lower cost and energy penalty relative to other Carbon Capture and Storage (CCS) options. This paper details the use of synthetic oxygen carriers composed of 20wt% CuO, Mn2O3 and NiO impregnated on Fe2O3 in CLC with Victorian brown coal as a fuel. The investigation used a variety of experimental equipment including a fluidized bed reactor, Thermogravimetric Analyser (TGA) and Temperature Programmed Reduction (TPR) unit. The oxygen carrier samples were characterized using techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Accelerated Surface Area and Porosimetry (ASAP). The characterization also included in situ high temperature XRD using synchrotron radiation to study the changes in the lattice parameter and crystal size of Fe2O3 as a function of temperature in a CLC-like environment. It was observed that the synthetic oxygen carriers demonstrated greater performance and enhanced reactivity over Fe2O3 with the NiO impregnated sample having the highest CO2 conversion efficiency. The synchrotron based in situ XRD study showed that the crystal size of the oxygen carrier increased after one redox cycle. This was also observed in the SEM micrographs of the used samples and is due to coalescence of the grains. Thermochemical modelling was carried out to generate an Ellingham diagram and it was found that the theoretical and experimental values did not conform well and this was attributed to the algorithm used by the software. It was found that all the synthetic oxygen carriers demonstrated superior performance over Fe2O3. However, the viability of using synthetic oxygen carriers in a larger scale will depend on the economics of their production.

Physicochemical Characteristics of Fine Ambient Aerosol from Quasi-Rural Area in Southern Poland

hour samples of PM 1 (submicron particles, aerodynamic diameters ≤1 µm) and PM 2.5 (fine particles, aerodynamic diameters ≤ 2.5 µm) were collected at a quasi-rural area in Raciborz (1 January- 30 June 2011). The samples were analysed for carbon (organic and elemental), water-soluble ions (Na + , NH 4 + , K + , Mg 2+ , Ca 2+ , Cl - , NO 3 - , SO 4 2- ) and concentrations of 21 elements with a carbon analyser (Sunset Laboratory Ltd.), an ion chromatograph (Herisau Metrohm AG) and an Epsilon 5 spectrometer (PANalitycal), respectively. To perform the monthly mass closure calculations for PM 1 and PM2.5, chemical components were categorized into the organic matter (OM), elemental carbon (EC), secondary inorganic aerosol (SIA), crustal matter (CM), Na/K/Cl (sum of Na + , K + and Cl - concentrations), other elements (OE) and unidentified matter (UM). The results show that the particulate matter (PM) concentrations and its chemical composition are mainly influenced by the anthropogenic emissions (coal, waste and biomass combustion in home furnaces and energy production based on hard and brown coal combustion). On the other hand, the secondary organic and inorganic (to a lesser extent) aerosols constitute a considerable part of the PM mass. The findings indicate serious problems related to the possible reduction in the fine PM concentrations in southern Poland. Even though places such as Raciborz can be formally qualified as rural sites, such areas in southern Poland do not necessarily have low PM concentrations (lower than in cities) or chemical compositions of fine particles different from those in cities.

Experimental investigation of fluidized bed chemical looping combustion of Victorian brown coal using hematite

An experimental investigation on chemical looping combustion (CLC) of Victorian brown coal is carried out in a fluidized bed of hematite. The aim of this study is to understand the feasibility of Victorian brown coal CLC as very little technical information is currently available on the process using these coals. The in situ CLC experiments are first performed using a thermogravimetric analyzer (TGA). The TGA results show good performance of hematite as oxygen carrier over five multiple re-dox cycles under CO2 gasification environment. Therefore, further investigation is performed using a bench-scale fluidized bed that operates in a batch mode cyclically with reduction in CO2 environment, and oxidation in air. Several tests have been conducted to assess the impact of different temperatures, particle size of hematite and CO2 concentration in a flowing fluidizing gas medium. It is observed that the hematite particles of 100–150μm performed best with respect to carbon conversions that show an increasing trend with increasing temperature and CO2 concentration in the fluidizing gas.

Cu Recovery from Industrial Wastewater Via Low Temperature Combustion of Cu-loaded Brown Coal

Cu Recovery from Industrial Wastewater Via Low Temperature Combustion of Cu-loaded Brown Coal

Spatial and seasonal variability of the mass concentration and chemical composition of PM2.5 in Poland

The seasonal changes in ambient mass concentrations and chemical composition of fine particulate matter (PM2.5) were investigated in three locations in Poland. The analyses included PM2.5-bound hazardous benzo(a)pyrene (BaP), As, Ni, Cd, and Pb. The samples of PM2.5 were collected daily in Katowice (southern Poland, urban background site), Gdańsk, and Diabla Góra (northern Poland, urban and regional background sites, respectively) during 1-year-long campaign in 2010. Based on monthly ambient concentrations of PM2.5-bound carbon (organic and elemental), water-soluble ions (Na+, NH4 +, K+, Mg2+, Ca2+, Cl−, NO3 −, SO4 2−), and elements As, Ni, Cd, Pb, Ti, Al, Fe, the chemical mass closure of PM2.5 was checked for each of the four seasons of the year and for the heating and non-heating periods at each site. Also, the annual concentrations of PM2.5 were determined and the annual PM2.5 mass closure checked. At each measuring point, the PM2.5 concentrations were high compared to its Polish yearly permissible value, 25 μg/m3, and its concentrations elsewhere in Europe. The highest annual PM2.5 concentration, 43 μg/m3, occurred in Katowice; it was twice the annual PM2.5 concentration in Gdańsk, and thrice the one in Diabla Góra. The high annual averages were due to very high monthly concentrations in the heating period, which were highest in the winter. PM2.5 consisted mainly of carbonaceous matter (elemental carbon (EC) + organic matter (OM), the sum of elemental carbon, EC, and organic matter, OM; its annual mass contributions to PM2.5 were 43, 31, and 33 % in Katowice, Gdansk, and Diabla Góra, respectively), secondary inorganic aerosol (SIA), the Na_Cl group, and crustal matter (CM)—in the decreasing order of their yearly mass contributions to PM2.5. OM, EC, SIA, Na_Cl, and CM accounted for almost 81 % of the PM2.5 mass in Katowice, 74 % in Gdańsk, and 90 % in Diabla Góra. The annual average toxic metal contribution to the PM2.5 mass was not greater than 0.2 % at each site. In Katowice and Gdańsk, the yearly ambient BaP concentrations were high (15.4 and 3.2 ng/m3, respectively); in rural Diabla Góra, the concentrations of BaP were almost equal to 1 ng/m3, the Polish BaP annual limit. The great seasonal fluctuations of the shares of the component groups in PM2.5 and of the concentrations of PM2.5 and its components are due to the seasonal fluctuations of the emissions of PM and its precursors from hard and brown coal combustion for energy production, growing in a heating season, reaching maximum in winter, and decreasing in a non-heating period. In Gdańsk, northern Poland, especially in the spring and autumn, sea spray might have affected the chemical composition of PM2.5. The greatest hazard from PM2.5 occurs in Katowice, southern Poland, in winter, when very high concentrations of PM2.5 and PM2.5-related carbonaceous matter, including BaP, are maintained by poor natural ventilation in cities, weather conditions, and the highest level of industrialization in Poland. In less industrialized northern Poland, where the aeration in cities is better and rather gaseous than solid fuels are used, the health hazard from ambient PM2.5 is much lower.

Thermogravimetric study of the combustion of Tetraselmis suecica microalgae and its blend with a Victorian brown coal in O2/N2 and O2/CO2 atmospheres

The combustion characteristics of microalgae, brown coal and their blends under O2/N2 and O2/CO2 atmospheres were studied using thermogravimetry. In microalgae combustion, two peaks at 265 and 485°C were attributable to combustion of protein and carbohydrate with lipid, respectively. The DTG profile of coal showed one peak with maximum mass loss rate at 360°C. Replacement of N2 by CO2 delayed the combustion of coal and microalgae. The increase in O2 concentration did not show any effect on combustion of protein at the first stage of microalgae combustion. However, between 400 and 600°C, with the increase of O2 partial pressure the mass loss rate of microalgae increased and TG and DTG curves of brown coal combustion shifted to lower temperature zone. The lowest and highest activation energy values were obtained for coal and microalgae, respectively. With increased microalgae/coal ratio in the blends, the activation energy increased due to synergy effect.

The advantage of virgin soil in rural service road constructions

Virgin soils as a result of geotechnical processes are element of road’s solid bottom. The bottom ought to have enough capacity and durability which is provided by proper virgin sub-grade’s enhancement. The sub-grade is road’s base course right bottom. It is possible to improve virgin soil’s parameters by road’s hydraulic binding agent. The agent is a mineral frame’s micro-particle extender or enhancement. The researches were focused to define main soil-cement compound’s mechanical parameter called CBR. Compounds consisted of rural virgin soils (five grain-size types) and two hydraulic agent types (endurance rates 3 MPa and 9 MPa). Hydraulic agent’s main component was activated fly ash and white cement (CEM I 42,5 MPa). The ash is from Pątnów Power Plant and is a result of brown coal burning. The researches answered that it is possible to exploit virgin soils in rural service road’s construction thanks to innovative road cements with binding qualities.

Thermodynamic evaluation of the compounds of gold, silver, and other trace elements formed upon the combustion of brown coal

The thermodynamically most probable main compounds of Ag, Au, Ge, Se, Sr, U, and ash-forming elements formed upon the combustion of brown coal, which was close in the composition of organic and mineral matter to coal from the Nazarovskoe deposit of the Kansk-Achinsk Basin, were determined. According to the experimental data, silver (in the form of AgO(g)) and gold (in the form of Au(g)) quantitatively passed into a gas phase at temperatures higher than 200 and 1179°C, respectively; selenium passed into a gas phase in the form of SeO2(g) at t = 800–1000°C and in the form of SeO2(g) and SeO(g) at t ≥ 1000°C. The SeO(g): SeO2(g) ratio increased with temperature. Germanium formed gaseous GeO(g) and GeO2 at t ≥ 1000°C, and the amount of the former dramatically increased with temperature.

Computational Fluid Dynamics Modeling on the Air-Firing and Oxy-fuel Combustion of Dried Victorian Brown Coal

The numerical modeling of the combustion of air-dried Victorian brown coal in O2/N2 and O2/CO2 mixtures with 21–30% O2 has been conducted via the use of computational fluid dynamics (CFD), ANSYS FLUENT 13.0, with the refined weighted-sum-of-gray-gases model (WSGGM), the single-film model with multiple surface reactions (i.e., char-O2, char-CO2, and char-H2O) for char particle, and the refined two-step mechanism for the oxy-firing of methane to mimic the volatile oxidation. The purpose of this study is to verify the experimental observations in a lab-scale drop-tube furnace (DTF) and to promote the understanding on the details underpinning the combustion characteristics of Victorian brown coal, the youngest coal in the world and the single largest source for power generation in Victoria, Australia. As confirmed, the modeling results show good agreement with the experimental measurements on the particle temperature, coal ignition delay photographed by a high-speed camera, carbon burnout rate, and particle velocity. The air-dried Victorian brown coal bears an extremely high reactivity for devolatilization and char-O2 and char-CO2 reactions. The inherent moisture in coal was released with volatile matter simultaneously rather than as that predicted by the CFD wet combustion module for pulverized coal with surface moisture. Increasing the secondary gas temperature greatly narrowed coal ignition delay caused by the substitution of 21% O2 balanced in CO2 for air. At the furnace temperatures of 1073 and 1273 K, the contribution of char-CO2 to coal burnout reached approximately 10 and 25% in the oxy-fuel mode, respectively, which, in turn, reduced the coal particle temperature by a maximum of 300 K. To achieve an identical flue gas temperature with the air-firing case, the use of 30% O2 in CO2 is essential. However, the radiation heat flux match can be achieved by the substitution of 27% O2 in CO2 for air.

Oxy-fuel fluidized bed combustion using Victorian brown coal: An experimental investigation

Oxy-fuel combustion is a promising power generation technology due to its potential for easier CO2 separation and capture. This when combined with fluidized bed combustion offers additional advantages like fuel flexibility, uniform temperature distribution, low NOx emissions and in-bed SO2 capture via sorbent addition. Although few studies have addressed the oxy-fuel fluidized bed combustion of lignites, its applicability using Victorian brown coal has remained unexplored. From experiments in a bench-scale fluidized bed under oxy-fuel combustion condition using Victorian brown coal, this study finds that the flue gas CO2 concentration increases with oxygen concentration and steam in the feed gas while the effect of temperature is modest between 850°C and 900°C. The addition of steam lowers the trace element retention in ash; this may indirectly affect their partitioning behavior. These results are important for selection of operating conditions for oxy-fuel fluidized bed combustion of Victorian brown coal.

Numerical Modelling of Oxy-Fuel Combustion in a Full-Scale Tangentially-Fired Pulverised Coal Boiler

This paper presents a computational fluid dynamics (CFD) modelling study to investigate Victorian brown coal combustion in a 550 MW utility boiler under the air-fired (standard) and three oxy-fuel-fired cases. The standard case was modelled based on the real operating conditions of Loy Yang A power plant located in the state of Victoria, Australia. A level of confidence of the present CFD model was achieved validating four parameters of the standard combustion case, as well as the previous preliminary CFD studies which were conducted on a lab-scale (100 kW) unit firing lignite and propane under oxy-fuel-fired scenarios. The oxy-fuel combustion cases are known as OF25 (25vol. % O2 concentration), OF27 (27vol. % O2 concentration), and OF29 (29vol. % O2 concentration). The predictions of OF29 combustion case were considerably similar to the standard firing results in terms of gas temperature levels and radiative heat transfer compared with OF25 and OF27 combustion scenarios. This similarity was because of increasing the residence time of pulverised coal (PC) in the combustion zone and O2 concentration in feed oxidizer gases. Furthermore, a significant increase in the CO2 concentrations and a noticeable decrease in the nitric oxides (NOx) formation were noted under all oxy-fuel combustion conditions. This numerical study of oxy-fuel combustion in a full-scale tangentially-fired PC boiler is important prior to its execution in real-life power plants.

Numerical Modelling of Coal Combustion Processes in the Vortex Furnace with Dual-Port Loading

The work is devoted to numerical simulation of pulverized-coal combustion processes in the vortex furnace which is a prospective design of a boiler unit for thermal power plants. New modification of this design characterized by additional tangential-injection nozzle located at the bottom of combustion chamber has been studied. Numerical results for the case of Siberian brown coal combustion in this vortex furnace with dual-port loading are presented, including 3-D aerodynamic structure, the fields of temperatures, radiated heat fluxes, species and dispersed phase concentrations, and NOx emissions.

Combustion and thermal decomposition characteristics of brown coal and biomass

Among the fossil fuels, the brown coal is a great deal of resources. However, it is hardly used due to the high moisture content and low calorific value. It has both the week points such as spontaneous combustion and high volatile content and the strong points such as the low-sulfur and low ash content. If we overcome these week points, the using amount of brown coal would be increased. Also, it is well known that biomass is one of the important primary renewable energy sources because of carbon neutral energy. Furthermore, the utilization of biomass has been more and more concerned with the depletion of fossil fuel sources as well as the global warming issues. Combustion and thermal decomposition of biomass is one of the more promising techniques among all alternatives proposed for the production of energy from biomass. In this study, combustion of brown coals and mushroom waste was done. Mass change of samples and emission of hydrocarbon components were measured. As the results, we obtained combustion rate constant. Also activation energy was calculated in char combustion step. Hydrocarbon components were more generated in low oxygen concentration than high. Emission amount of hydrocarbon components in mushroom waste was significantly increased comparing to brown coal.