Coal Thermal Power Stations Research Articles

Evaluation of plant species for air pollution tolerance and phytoremediation potential in proximity to a coal thermal power station: implications for smart green cities.

In metropolitan areas, air pollution poses a significant threat, and it is crucial to carefully select plant species that can tolerate such conditions. This requires a scientific approach based on systematic evaluation before recommending them to executive bodies. This study aimed to determine the air pollution tolerance index (APTI), dust retention capacity, and phytoremediation ability of 10 plant species growing in and around a lignite-based coal thermal power station. The results showed that Ficus benghalensis L. had the highest APTI, followed by Mimusops elengi L., Ficus religiosa L., Azadirachta indica A. Juss., and Annona reticulata L. F. benghalensis also showed the highest pH of leaf extract, relative water content, total chlorophyll, and ascorbic acid content, as well as the highest dust capturing capacity. Among the ten plant species, F. benghalensis, M. elengi, F. religiosa, A. indica and F. racemosa were identified as a tolerant group that can be used for particulate matter suppression and heavy metal stabilization in and around thermal power plants. These findings can inform the selection of plants for effective green infrastructure in smart green cities, promoting the health and well-being of urban populations. This research is relevant to urban planners, policymakers, and environmentalists interested in sustainable urban development and air pollution mitigation.

Experimental Study of the Performance of a Venturi-Meter with Suspended Gas-Solid Flow

ABSTRACT Due to the urgent need for electricity sources in Egypt, this investigation is an attempt to prepare a metering tool for measuring the flow rate of the suspended gas-solid mixture flows in coal thermal power stations. One of the simplest methods for accurately measuring the flow rate of pulverized coal in the thermal power stations is the venturi meter. In the present work, different geometrical models have been designed and applied for measuring air-coal mixture flow rate, considering the effect of different operational parameters on the pressure sensitivity, pressure recovery and performance of the venturi models. The measurements showed the effects of these parameters on the pressure drop and the pressure distribution. New charts have been deduced from the experimental data for seven non-standard venturi models that shows different effects of particle size, loading ratio and throat length of venturi. From the experimental results a new correlation for two-phase flow discharge coefficient is deduced in the present study and comparison between the experimental and calculated is done with error percentage from +25% to -20%.

TECHNICAL SOLUTIONS FOR DECREASING NOX EMISSIONS AT COAL THERMAL ELECTRIC POWER STATIONS

Most power-generating units at the Ukrainian thermal electric power stations were designed to burn hard coal mined in Ukraine, but today due to physical depreciation of the stations, those units are in non-project manoeuvring peaking operation what leads to the increase in both the specific fuel equivalent consumption and in harmful environmental emissions. The purpose of the research is to develop recommendations on the selection of optimal technical solutions aimed at reducing NOx emissions of oxides at the operating boilers of Burshtyn thermal electric power stations (TEPS) under the conditions of regime-technological measures. The article analyzes the main approaches to developing and selecting technological methods aimed at reducing emissions of coal thermal power stations and identifies prospects for their work in accordance with modern environmental requirements. The mechanisms of the transformations the organic fuel bound nitrogen undergoes when heated are determined. To reduce the amount of NOx emissions in combustion products, it is offered to apply the regime-technological mode of the preliminary heating the pulverized coal mixture. The results of thermo chemical studies of coal samples used at Burshtyn TEPS are presented. The temperature ranges are determined at which the maximum emissions of volatile combustible compounds takes place before to the upper flammability limit of the pulverized coal mixture is reached. It was determined that under the conditions of actual burning process, there is a clear sequence: a release of volatile components and burning of the coke residue; heating of the pulverized coal mixture; emission of volatile combustible compounds; their burning; heating of the coke residue up to initiation of its combustion; the coke residue burning-out. A pulverized coal stream is brought into the furnace without being preliminary mixed up with air. While burning the pulverized coal stream, fuel particles are heated and degassed in the zone immediately adjacent to the burner section where there is a shortage of oxygen, whereas the oxygen concentration in the flow is a gradually increasing. The regime-technological measures that are aimed at inhibiting NOx oxides formation by preliminary heat treatment of the pulverized coal mixture; they make it possible to obtain the maximum emissions of volatile combustible compounds before the upper flammability limit of the pulverized coal mixture is reached. It was found out that heat treatment should be carried out at temperature from 540-580° C. This is the temperatures range when the maximum emission of volatile combustible compounds takes place. After this combustion occur in an environment that is practically devoid of oxygen, where competing reactions of formation of volatile components and molecular nitrogen occur simultaneously. Thereafter, combustion can proceed in the practically oxygen-free environment with competing parallel reactions the forming volatile components and molecular nitrogen. This method allows to almost halving the concentration of nitrogen oxides in flue gases.

Suppression of nutrient release from freshwater lake sediments using granulated coal ash

Abstract In order to investigate the applicability of granulated coal ash (GCA), a by-product of coal thermal power stations, to freshwater lakes, two incubation experiments (fall and summer experiments) were conducted using large-volume vessels and sediments taken from eutrophic lakes. The phosphorus and nitrogen release fluxes in the vessels with GCA (up to 2.9 mg m−2 d−1 for total phosphorus and 23.9 mg m−2 d−1 for total nitrogen) were considerably smaller than those in the vessels without GCA (up to 8.9 mg m−2 d−1 and 56 mg m−2 d−1, respectively), except in the case of phosphorus in the fall experiment, and thus the phosphorus concentration released from the vessel without GCA under anoxic conditions in the summer experiment was extraordinarily higher (over 1.5 mg l−1) than those in the other vessels (less than 0.31 mg l−1). Supplementary experiments with smaller columns indicated that the chemical effect of GCA was on a similar level with its physical effect and that the threshold phosphorus concentration for removing it was lower in freshwater than seawater. The chromium level slightly exceeded the standard for drinking water and the development of technology to suppress its release is a future challenge.

Coal-water slurries containing petrochemicals to solve problems of air pollution by coal thermal power stations and boiler plants: An introductory review

This introductory study presents the analysis of the environmental, economic and energy performance indicators of burning high-potential coal water slurries containing petrochemicals (CWSP) instead of coal, fuel oil, and natural gas at typical thermal power stations (TPS) and a boiler plant. We focus on the most hazardous anthropogenic emissions of coal power industry: sulfur and nitrogen oxides. The research findings show that these emissions may be several times lower if coal and oil processing wastes are mixed with water as compared to the combustion of traditional pulverized coal, even of high grades. The study focuses on wastes, such as filter cakes, oil sludge, waste industrial oils, heavy coal-tar products, resins, etc., that are produced and stored in abundance. Their deep conversion is very rare due to low economic benefit. Effective ways are necessary to recover such industrial wastes. We present the cost assessment of the changes to the heat and power generation technologies that are required from typical power plants for switching from coal, fuel oil and natural gas to CWSPs based on coal and oil processing wastes. The corresponding technological changes pay off after a short time, ranging from several months to several years. The most promising components for CWSP production have been identified, which provide payback within a year. Among these are filter cakes (coal processing wastes), which are produced as a ready-made coal-water slurry fuel (a mixture of flocculants, water, and fine coal dust). These fuels have the least impact on the environment in terms of the emissions of sulfur and nitrogen oxides as well as fly ash. An important conclusion of the study is that using CWSPs based on filter cakes is worthwhile both as the main fuel for thermal power stations and boiler plants and as starting fuel.

Are physico-chemical soil characteristics key factors to select the polycyclic aromatic hydrocarbons extraction procedure?

ABSTRACTThe aim of this work was to assess the impact of soil characteristics and constituents in the total extraction of hydrophobic organic pollutants, such as polycyclic aromatic hydrocarbons (PAH), in real polluted soil samples from different sources. Soil samples were obtained from a wood creosote treatment plant, in the vicinity of a metallurgy industry and coal thermal power stations. Soils showed a wide diversity of textures, organic matter (OM) and CaCO3 content, pH and electrical conductivity to assure representativeness of multiple situations. Two extraction procedures with soft (solid–liquid extraction, SLE) and intense (pressurised liquid extraction, PLE) extraction power were used to determine the total concentration of PAH in soils. Results obtained showed that soil properties affect the effectiveness of the extraction procedures tested. The validation of PAH extraction procedure with a reference soil did not confirm that the procedure was adequate for all kinds of soil. Results showed that OM content and clay were the main soil characteristics that should be taken into account to select the most adequate PAH extraction procedure for any given polluted soil.

Environmental Safety of Coal Thermal Power Stations

Prospects of using the local feedstock base at coal thermal power stations with an efficient technological structure of environmental safety are analyzed by the example of the Kamchatka krai. The necessity of active reduction of the anthropogenic effect on the environment is shown in the comparative aspect of abiotic and anthropogenic ecological factors. The calculated characteristics by emissions of harmful substances into the atmosphere from the steam-turbine power-generating unit using coal of the Krutogorovskoe deposit are presented. Possibilities of implementation of the flowsheet with the coal gasification and steam-gas installation based on the synthesis gas are considered.

Influence of metakaolin on chemical resistance of concrete

Nowadays the most suitable and widely used construction material is concrete. We could develop concrete for every request in connection with the properties of fresh concrete and the quality of hardened concrete, too. The demand is rising in application of special concretes, like high performance and ultra high performance concretes (HPC, UHPC). These are usable in extreme natural circumstances or in very corrosive surroundings (for example: sewage farm, sewer, cooling tower, biogas factories). The pH value of the commercial sewage is between 7–8, but this value is often around 4 or less. The concrete pipes, which transport the sewage, are under corrosion, because above the liquid level sulphuric acid occurs due to microbes. Acidic surroundings could start the corrosion of concrete. When the pH value reduces, the influence of the acids will increase. The most significant influence has the sulphuric acid. The pH value of sulphuric acid is about 1, or less. Earlier in the cooling towers of coal thermal power stations used special coating on the concrete wall. Recently application of high performance concrete without polymeric coating is more general. Cementitious supplementary materials are widely used to protect the concrete from these corrosive surroundings. Usually used cementitious supplementary materials are ground granulated blastfurnace slag (GGBS), flying ash (FA) or silica fume (SF). In the last years there has been a growing interest in the application of metakaolin. Metakaolin is made by heat treatment, calcinations of a natural clay mineral, kaolinite. In our present research the chemical resistance of mortars in different corrosive surroundings (pH=1 sulphuric acid; pH=3 acetic acid) and the chloride ion migration were studied on series of mortar samples using rapid chloride migration test. Cement paste and mortar samples were made with 17% metakaolin replacement or without metakaolin. The following cements were used: CEM II/A-S 42.5 N, CEM I 42.5 N-S. We concluded that the replacement of cement by metakaolin results in significant increases in compressive and tensile strengths and it prevents the infiltration of harmful substances.

Dynamics of sulfur-containing admixtures in the atmosphere around a point source—the Baikal Pulp and Paper Plant on the southeast coast of Lake Baikal

A complex of organic and inorganic sulfur compounds have been measured for the first time in the vicinity of a point anthropogenic source—the Baikal Pulp and Paper Plant (BPPP) on the southeast coast of Lake Baikal; their spatial distribution and possible chemical transformation depending on the meteorological conditions and the time of day have been estimated. It is shown that the different heights of the emission of the sulfur compounds by departments of the plant and the coal thermal power station are responsible the different behavior of the corresponding admixtures in the plant’s surrounding.

石炭灰/NiCr 合金積層焼結体の焼結挙動

Coal fly ash and NiCr alloy powder stacked layer by layer (FGM) were prepared by spark plasma sintering. The coal fly ash was produced by Misumi coal thermal power station (Chugoku Electric Power Co., Inc.), and 80 mass% nickel and 20 mass% chromium (Fukuda Metal Foil & Powder Co., Ltd) were used as source materials. The sintering was done at 1000°C in a graphite die. X-ray diffraction patterns of the sintered coal fly ash materials indicated that the mullite (3Al2O3•2SiO2) and silica (SiO2) phases were predominant. Direct joining of coal fly ash and NiCr causes a fracture at the interface due to a mismatch of thermal expansion. Cracks in the FGMs were observed between the two layers when the difference of linear thermal expansion coefficient (α) was over 4.2×10-6 K-1, while no cracks were detected in stable FGMs when the difference was less than 4.0×10-6 K-1.

Sintering Properties of Functionally Graded Materials Using Coal Fly Ash and NiCr-Based Alloy Powder

Functionally graded materials (FGMs) were prepared by spark plasma sintering using coal fly ash and NiCr alloy powder. The coal fly ash was produced by Misumi coal thermal power station (Chugoku Electric Power Co., Inc.), and 80 mass% nickel and 20 mass% chromium (Fukuda Metal Foil & Powder Co., Ltd) were used as source materials. The sintering was done at 1000 � C in a graphite die. X-ray diffraction patterns of the sintered coal fly ash materials indicated that the mullite (3Al2O3� 2SiO2) and silica (SiO2) phases were predominant. Direct joining of coal fly ash and NiCr causes a fracture at the interface due to a mismatch of thermal expansion. Cracks in the FGMs were observed between the two layers when the difference of linear thermal expansion coefficient (� ) was over 4:2 � 10 � 6 K � 1 , while no cracks were detected in stable FGMs when the difference was less than 4:0 � 10 � 6 K � 1 . [doi:10.2320/matertrans.MK200703]

Influence of two different fly ashes on the hydration of portland cements

Fly ashes from the combustion of coal thermal power stations are commonly incorporated into portland cements and/or concretes and mortars. The chemical and morphological composition of fly ashes, together with their particle size, make them suitable as pozzolanic(non-calcic) or pozzolanic/hydraulic(highly calcic) additions to manufacture such building materials. This work focuses on the incorporation of two different fly ashes (non-calcic but of very different Fe2O3(%) contents, fineness and morphology) to two ordinary portland cements (of very different mineralogical composition as well), to determine the effects those have and the interactions they produce in the hydration reactions of portland cement. The main techniques employed for this study have been: conduction calorimetry and Frattini test; secondary techniques applied have also been: determination of setting times and analysis by X-ray diffraction and SEM. Analysis of the results obtained permitted to find different effects of fly ash addition on the hydration reactions of portland cements. Thus, dilution and stimulation effects augment with the increased fly ash percentage. Delay and acceleration of the reactions depend mainly on the type of portland cement and are accentuated with increased fly ash contents. Their behaviour as concerns heat dissipation mainly, depends on the type of fly ash used and is more pronounced with increased cement replacement. On the other hand, the pozzolanic activity of these fly ashes has been revealed at 7 and 28 days, but not at 2 days. Finally, pozzolanic cements can be manufactured using different portland cements and/or types of fly ashes, in the appropriate proportions and compatible qualities, depending on the effect(s) one wish to enhance at a specific age, which is according to previous general conclusions drew out of sulphate attack and chloride attack researches.

Quantification of fly ash in cements and mortars by means of gamma spectrometry

A method is proposed here to quantify fly ash in cements and mortars using high resolution gamma spectrometry assuming provided the source of the fly ash is known. The method was tested for nine samples of Portland 450 cement and fly ash from coal thermal power stations in Andorra (Teruel), Cercs (Barcelona) and Alcudia (Mallorca) which correspond to the low, high and very high calcium content types, respectively. In addition, two samples of fly ash from Cercs, standardized sand and Portland 450 cement were also analysed. The specific activity in Bq/Kg of two isotopes of the decay series of 238U ( 214Pb and 214Bi), another of the decay series of 232Th ( 228Ac), in addition to 40K was used for the quantification.

Natural radiation in fly ashes from coal thermal power stations in Spain

Specific activity in samples of fly ashes from Spanish coal thermal power stations at Aboño (Asturias), Andorra (Teruel), Alcudia (Mallorca) and Cercs (Barcelona) was analysed by gamma ray spectrometry. The values obtained permit us to quantify the presence of different natural radionuclides from 232Th, 238U, 235U series and 40K. The models are defined on the basis of these data to calculate the dosimetric impact caused by the use of fly ashes in the concrete.

石炭バンカーの閉塞に対する改良ホッパおよび壁材の効果

Experiments were carried out on the discharge of wet coals from experimental bunkers with a capacity of about 4m3. These bunkers were reduced to a scale of one-sixth the actual size of those in a coal thermal power station. Consequently, the coal bunker must be completely designed as a type of mass flow.An improved hopper was proposed in order to reduce the critical size of hopper outlet. The improved hopper was a regular pyramidal hopper joined to a conical hopper, and a prismatic insert was installed between each opposite wall of the pyramidal hopper.A method is described for the estimation of the critical size of the bridge in the hoppers at the commencement of flow on the basis of the conditions of the static state of stresses exerted by the bulk solid. The estimated values of the critical outlet size, using the fixed volume shear cell results, were in good agreement with the experimental results of the discharge.The experimental results also indicate that the slope angle of the hopper walls was reasonably determined from both the angle of internal friction and the angle of wall friction according to Jenike's approach. Moreover, remnants of coal that adhered to the bunker walls were strongly affected by the wall materials used, such as steel and ultra high molecular weight polyethylene.

石炭灰有効利用の展望

Most of coal ash produced in the coal thermal power stations in Japan has been disposed for landfilling on the land and in the sea. However, in the near future, it is anticipated that newly built power stations will face the sevier problems of the coal ash disposal because of the deficient spaces for disposal. On the other hand, it is apparent that there will be a shortage of the natural resources for construction, for example, limestones, clays, aggregates and sonds. Therefore, if the coal ash is effectively utilized for the construction material, the problem of the coal ash disposal in the power stations will be solved.In some countries, the technology of the coal ash utilization has been developed, and in fact, the coal ash produced from the power stations are successfully used for the cement manufacturing and also for the concrete replacing. In this paper, the author illustrated some examples of the successful utilization of the coal ash and pointed out some problems to be solved in Japan. It is necessary to establish and develop the technology for coal ash utilization, which includes the upgrading of coal ash based on the economical advantage of the final products.