Coal-burning Power Station Research Articles

The possible application of fly ash (FA) to ameliorate acid mine water (AMD) for irrigation of potato (Solanum tuberosum L.)

Some areas in Johannesburg abounds with mine wastes namely, acid mine drainage (AMD) as well as fly ash (FA), which are by-products of gold mining and coal burning, respectively. Studies show that a solution formed through mixing these wastes neutralises the acidity of AMD and is an alternative source of irrigation. While studies show improved growth and yield of plants irrigated with fly ash-amended AMD, there are rarely sufficient studies conducted in South Africa showing evidence of altered pH of AMD and that food crops irrigated with fly ash-amended AMD exhibit improved concentration of essential nutrient elements. In this study, AMD was sourced from a gold mine in Johannesburg and fly ash collected from a coal-burning power station in the Mpumalanga Province, mixed at 1:0, 1:1, and 3:1 (w/v) of fly ash to AMD and used to irrigate potatoes. The objective was to assess whether the solutions of FA-amended AMD alter the pH of the AMD and to evaluate if irrigating potatoes with the aforementioned improve the concentration of essential nutrient elements and heavy metals in the tubers. Results show that the pH of AMD was increased in the 1:0 and 1:1 solutions but decreased in the 3:1 solution. The concentrations of Pb and Co were decreased in tubers irrigated with the 50 % AMD and 75 % AMD while that of Ni and Cd were markedly increased in tubers irrigated with solutions of fly ash-amended AMD. In the main, the potato tubers exhibited significantly higher concentrations of Al, Mo, Cu, Ca, Mg, and Zn when irrigated with fly-ash-amended AMD. The pH range levels from FA-AMD treated samples were within the acceptable pH range (5.5–6.5) which is acceptable for water that could be used for irrigation of crops. Also, the decreased Co and Pb and improved concentration of essential nutrient elements indicate that the constituents absorbed large quantities of the heavy metals while releasing the nutrients. In conclusion, the selected fly ash has proven as an alternative low-cost readily-available, affordable, and accessible adsorbent that neutralize the acidity of AMD, decrease the concentration of heavy metals, and increase the concentration of essential nutrient elements. Importantly, the liming potential among other traits of the fly ash improved the quality of the AMD such that the wastes were proven in this study suitable to irrigate potatoes.

Bottom ash treatment by using seawater with Citrus aurantifolia

The combustion process of coal from a coal-burning power station in TNB Janamanjung Sdn. Bhd. for production of energy was produced a primary by-product called coal ash. The huge amount of bottom ash was considered harmful to the environment and typically disposed of on-site disposal systems without any further use. The environment can be polluted since the toxic elements such as heavy metals that exist in the ash could pose a danger to public health. To overcome these problems, an effective treatment needs to be done to overcome the problems. The purpose of this research is to study the possibility of developing a new technique to reduce heavy metal elements by using seawater as a washing method and Citrus aurantifolia as leaching methods. A good alternative from the use of citric acid from the Citrus aurantifolia was discovered to be substitute strong acids such as HCl in the leaching process since citric acid can react as an organic acid which fewer negative effects compared to the stronger acid to humans and the environment. The bottom ash was rinsed and soaked in the seawater for 24 hr before the leaching process by using Citrus aurantifolia. The result showed that the heavy metals content such as copper (Cu), zinc (Zn), and arsenic (As) can be decreased after the removal process. In fact, the results show that the heavy metal removal up to 92% for As when the bottom ash was soaked until 72 hr but for Cu and Zn, the removal efficiency higher when the bottom ash was soaked at 20 hr. In conclusion, the optimum time to remove heavy metal from bottom ash by using Citrus aurantifolia was determined but the efficiency differs with the time taken to soak the bottom ash in the acid solution.

Reducing Heavy Metal Element from Coal Bottom Ash by Using Citric Acid Leaching Treatment

Coal ash is the residue that is produced during coal combustion for instance fly ash, bottom ash or boiler slag which was primarily produced from the combustion of coal. With growth in coal burning power station, huge amount of coal bottom ash (CBA) considered as hazardous material which are normally disposed in an on-site disposal system without any commercialization purpose. Previous researchers have studied the extraction of silica from agricultural wastes such as palm ash and rice husk ash (RHA) and CBA by using leaching treatment method. In this study, the weaker acid, citric acid solution was used to replace the strong acid in leaching treatment process. Result showed that the heavy metal content such as Copper (Cu), Zinc (Zn) and Lead (Pb) can be decrease. Meanwhile the silica can be extracted up to 44% from coal bottom ash using citric acid leaching treatment under the optimum reaction time of 60 minutes with solution temperature of 60°C and concentration of citric acid more than 2%.

Utilization direction of industrial raw products built-up in power station ash dumps

Nowadays hundreds million tons of ash and slag waste (ASW) is produced in Russia yearly. Large territories are needed in order to store such a big waste volume. Besides, it is necessary to conduct special engineering and ecological work at the design and usage stages of this structure. The goal of the research is to outline acceptable ASW utilization methods accumulated in coal burning power station ash dumps and to determine the order of activities to solve the problem. The research methods: experimental where Kansk-Achinsk and Kuznetsk coals are the object of the research. Besides, review of relevant to the problem literature and normative documentation was done to determine activities order, possible ways and limitations of the problem solving. We elucidated that ASW transportation to depleted coal quarries to restore them is essential to arrange in order to solve the problem of ASW utilization. As to new produced ASW, they should be divided into groups according to application field (mostly in construction). The groups correspond to boiler unit load operation. After coal combustion ash is stored in special places (reservoirs, silos). Therefore modern boiler unit might be seen as a production complex of steam and ash and slag material of an adequate quality.

The Chemical Composition of Natural Waters and Water Extracts of the Soils of the Industrial Area of Coal-Burning Power Station “Partizanskaya”

Power stations provide a huge influence on the environment. This influence can be diverse and integrated: (1) land avulsion, (2) dusting from the open storage spaces of fuel, ash and slags, (3) huge amounts of ash-slug wastes containing toxic metals. The aim of the research is to evaluate the effect of ash-slug wastes of the coal-burning power station Partizanskaya on the ecological state of soils and water bodies. The waters of the Lozoviy Stream are polluted mostly with the residual iodine, bromine, silicium compounds and sulphides. Ash-slags of the coal-burning power station Partizanskaya can be an environmental hazard. The obtained information about the properties of the abiotic components of the industrial area of the coal-burning power station Partizanskayaash-slags, soils and water bodiesare the first step in studying the environmental situation in this area. One of the possible solutions aimed to improve the environmental situation in the industrial area of the coal-burning power station Partizanskaya is recultivation of the ash dump and development of the technologies for the usage of the ash in the household economy.

Transformation of the Physical Properties of the Soils of the Industrial Area of Coal-Burning Power Station “Partizanskaya”

Power stations provide a huge influence on the environment. This influence can be diverse and integrated: (1) land avulsion, (2) dusting from the open storage spaces of fuel, ash and slags, (3) huge amounts of ash-slug wastes containing toxic metals. The aim of the research is to evaluate the effect of ash-slug wastes of the coal-burning power station (CBPS) Partizanskaya on the ecological state of soils. Transformation of the physical properties of the soils appears in the increasing fraction of coarse grain size, reducing of the sludge content in the soils, which lowers the surface area of the soils and their sorption properties. Ash particles input to the surface of soil leads to the decrease in their antierosion properties. Water capacity properties of the soils are reduced and with the moisture up to 50% soils can flow. The obtained information about the properties of the abiotic components of the industrial area of the CBPS Partizanskayaash-slags, soils are the first step in studying the environmental situation in this area. One of the possible solutions aimed to improve the environmental situation in the industrial area of the CBPS Partizanskaya is recultivation of the ash dump and development of the technologies for the usage of the ash in the household economy.

Mineralogy and Mobility Patterns of Chemical Species in Weathered Coal Fly Ash

Chemical interactions of disposed coal fly ash with O2, CO2, and infiltrating rain-water lead to chemical alteration, flushing/leaching of soluble chemical species locked in different physico-chemical forms as the coal fly ash is aging. This study was carried out to gain insight into the chemical alterations and its effects on the mobility patterns of chemical species in weathered coal fly ash. Weathered coal fly ash samples of ages 1 year and 20 years were sampled at a coal burning power station in the Mpumalanga Province, South Africa. The chemical and mineralogical compositions of the weathered coal fly ash were investigated using X-ray fluorescence spectrometry, inductive coupled plasma-optical emission spectrometry, ion chromatography, X-ray diffraction, and Fourier transform infrared spectroscopy. X-ray fluorescence results showed the presence of major oxides, such as SiO2, Al2 O 3, Fe2 O 3, while CaO, K2O, TiO2, MnO, MgO, P2 O 5, and SO3 occur in minor concentrations. The major elements, such as Fe, Si, Mg, K, and Mn, showed increasing trends down the depth of the core, while Ti and Al show decreasing trends down the depth of the core (20-year-old coal fly ash). Trace metals, such as P and Zn, show increasing trends down the depth, while Ba, Ni, Pb, Sr, V, and Cr increase up the depth of the core (20-year-old ash). The trace metals distribution patterns in 1-year-old ash showed increasing trends down the depth of the core for Cr, Ni, Pb, Y, S, and P, while Ba and Sr decrease down the depth of the core. Major mineral phases as revealed by X-ray diffraction include quartz and mullite. Other minerals identified are hematite, calcite, lime, anorthite, mica, and enstatite. The pH of interstitial pore water for 1-year-old and 20-year-old coal fly ash ranged from 9.0–10.6 and 7.2–9.9, respectively, while in the 2-week-old coal fly ash ranged from 9.9–10.9. Analysis of extracted pore water shows that several toxic metals, such as B, Cr, As, Mo, and Se, are leaching from the weathered ash. The core ash samples in contact with the atmosphere and those at the saturation point record the highest availability of chemical species, such as Mg, Ca, Fe, K, Na, B, Cr, As, Mo, and Se in pore water. The 1-year-old and 20-year-old coal fly ash cores showed a lower pH and greater leaching/flushing of the soluble buffering constituents than the 2-week-old placed ash.

Dispersion of As and selected heavy metals around a coal-burning power station in central Slovakia

A power station in central Slovakia emitted arsenic (As) in large quantities for over 30 years as a result of burning As-rich brown coal. Nowadays emissions of As are low. Over the lifetime of the plant's operation over 3000 tonne of As have been emitted into the environment. This paper aims to examine the concentrations of As in the soil around the power station, and also to investigate whether the coal burnt in the plant, and consequently the emissions from it, contained raised levels of six further heavy metals. Soil concentrations were compared to ground level air As concentrations predicted by an air dispersion model. Coal samples were taken from the power station and analysed to determine concentrations of As, Zn, Pb, Cu, Cr, Ni and Cd. Soil samples ( n = 113) were taken up to 12 km from the plant along a transect designed to follow the valley floor in which the power station is situated. Soil samples were analysed for concentrations of those elements for which coal was tested. Concentrations of As in coal were high (AM 518 μg/g). Those of other heavy metals were, in general, low. Concentrations of soil As were substantially raised in the near vicinity of the plant but decreased within 5 km to concentrations similar to those in the rest of the district. Overall, levels within 10 km of the plant were slightly above those recommended for residential levels in the UK. Soil concentrations of other heavy metals were higher in the vicinity of the plant but none, overall was raised. Comparison of results from a previous air dispersion model of ground level air arsenic concentrations showed a moderate correlation ( r = 0.6) between modelled and measured values. Over its period of operation the power plant has contributed to raised levels of soil As in the local soils, though not substantially of other elements. Though now airborne As emissions are controlled, concern remains regarding soil arsenic concentrations and fugitive emissions from the plant that could be contributing to exposure of the local population and of the workforce.

Electricity generation: options for reduction in carbon emissions.

Historically, the bulk production of electricity has been achieved by burning fossil fuels, with unavoidable gaseous emissions, including large quantities of carbon dioxide: an average-sized modern coal-burning power station is responsible for more than 10 Mt of CO(2) each year. This paper details typical emissions from present-day power stations and discusses the options for their reduction. Acknowledging that the cuts achieved in the past decade in the UK CO(2) emissions have been achieved largely by fuel switching, the remaining possibilities offered by this method are discussed. Switching to less-polluting fossil fuels will achieve some measure of reduction, but the basic problem of CO(2) emissions continues. Of the alternatives to fossil fuels, only nuclear power represents a zero-carbon large-scale energy source. Unfortunately, public concerns over safety and radioactive waste have still to be assuaged. Other approaches include the application of improved combustion technology, the removal of harmful gases from power-station flues and the use of waste heat to improve overall power-station efficiency. These all have a part to play, but many consider our best hope for emissions reduction to be the use of renewable energy. The main renewable energy contenders are assessed in this paper and realistic estimates of the contribution that each could provide are indicated. It appears that, in the time-scale envisaged by planners for reduction in CO(2) emission, in many countries renewable energy will be unlikely to deliver. At the same time, it is worth commenting that, again in many countries, the level of penetration of renewable energy will fall short of the present somewhat optimistic targets. Of renewable options, wind energy could be used in the short to medium term to cover for thermal plant closures, but for wind energy to be successful, the network will have to be modified to cope with wind's intermittent nature. Globally, hydroelectricity is currently the largest developed source of renewable electricity, but future large-scale projects will probably be limited to the less-developed world: the best schemes in the developed countries have already been exploited. Wave and tidal can be looked on as medium- to long-term generators of electricity, as their respective industries are not as mature as competing renewable resources. Municipal solid-waste combustion and landfill gas technologies can also be seen as short term, as can their rural equivalents, agriculture and forestry waste. Any widespread exploitation of renewable energy will depend on being able to transmit the energy from source to point of use, so the implications for the electrical network from the penetration of substantial levels of renewable energy are presented. Effective management of renewable energy installations will require technical assessment of the range of exploitation strategies, to compare local production of, say, hydrogen and the more traditional transmission of electricity. Such resources will have to compete with others in any national, or grid, system and detailed economic analysis will be necessary to determine the deployment that best fits the trading regime under which the energy will be sold. Consideration will also be necessary to determine how best to control the introduction of this radically new resource such that it does not attract punitive cost overheads until it is mature enough to cope. Finally, it is inescapable that nuclear power is a proven technology that could take its place in any future generation portfolio. Unfortunately, suspicion and mistrust surround waste management and radioactivity release. Unless this is overcome, the lack of confidence engendered by this public mistrust may result in few, if any, new nuclear power stations being built. In the event of that decision, it is difficult to see how CO(2) levels can be significantly reduced: the irony is that nuclear energy may emerge as environmentally essential.

Assessment of environmental arsenic levels in Prievidza district.

A coal-burning power station in the Nitra Valley in central Slovakia annually emitted large quantities of arsenic (up to 200 tonnes) between 1953 and 1989. Since then, pollution-control measures have reduced arsenic emissions to less than 2 tonnes a year. However, the power station was still a source of airborne arsenic pollution. As part of an EU-funded study on exposure to arsenic and cancer risk in central and Eastern Europe we carried out a study of environmental levels of arsenic in the homes and gardens of residents of the district. Garden soil samples (n=210), house dust samples (n=210) and composite house dust samples (n=109) were collected and analysed using inductively coupled plasma atomic absorption spectroscopy (ICP-AES) at Imperial College. The mean arsenic content of coal and ash in samples taken from the plant was 519 microg/g (n=19) and 863 microg/g (n=22), respectively. The geometric mean (GM) arsenic concentration of garden soils was 26 microg/g (range 8.8-139.0 microg/g), for house dust 11.6 microg/g (range 2.1-170 microg/g) and for composite house dust 9.4 microg/g (range 2.3-61.5 microg/g). The correlation between the arsenic levels in soil and in house dust was 0.3 (P<0.01), in soil and composite house dust 0.4 and house dust and composite house dust 0.4 (P<0.01 for both), i.e., were moderate. Arsenic levels in both house dust and soil decreased with distance from the power station. Overall, levels in both fell by half 5 km from the point source. Weak correlations were seen between the total urinary arsenic concentrations and arsenic concentrations in composite house dust.

Identifying Fly Ash at a Distance from Fossil Fuel Power Stations

A method has been developed to identify fly ash originating at fossil fuel power stations, even at a distance where the ash level is lower by a factor of 1000 from that close to a source. Until now such detection has been difficult and uncertain. The technique combines collection of particles, measurement of magnetization and coercive field, and microscopy. The analysis depends on the fact that ash from iron sulfide in fossil fuels is in the form of spherical magnetite. These particles have a relatively high coercive field Hc, near 135 Oe, compared with airborne particulates from soil erosion which have an Hc of ∼35 Oe. The coercive field of any sample therefore gives an indication for the percentage of fly ash relative to the total amount of magnetic material that is airborne. The concentration of ash from a large, isolated coal burning power station is found to fall off with the distance from the source, approximately as D-1. As D increases there is a drop in Hc, associated with the reduced amount of fly ash relative to the airborne particulates from soil erosion.

Study on Technical Method for Sending CO2 into Deep Ocean with Pipe from Floating Platform

Concerning with the disposal of CO2 in ocean, technical aspects on sending CO2 into deep ocean with a long vertical pipe from a floating platform are treated in this paper.At first, the heat balance of liquid CO2, pipe, ice on the wall and the surrounding seawater is formulated under the equilibrium condition. In order to estimate the vertical temperature change of CO2 correctly, it is found that the heat insulating effects of the ice covered on the pipe wall should be taken into accout. The validity of the estimation method is confirmed with a laboratory test. A stainless pipe is fixed in a seawater-circulating tank and cold N2 gas is let flow in the pipe constantly. The temperature change of the N2 gas and the thickness of ice generated on the pipe wall are measured to be compared with calculated results.Secondly, case studies are performed on liquid CO2 recovered from a 1.0 GW-class coal burning power station. Here, the equipments and piping diagram are initially designed under the necessary condition that the temperature and the pressure of CO2 at the lower outlet are almost the same with those of surrounding seawater.

Epidemiological monitoring near a coal-fired power plant in Israel.

The Sharonim power plant is the first coal-burning Israeli power station. The yearly coal consumption will be 3.4 million t. The paper describes the environmental monitoring that will be carried out and also a health monitoring system that is being set up. The costs of this system are compared with that of an air pollution monitoring system.

Fusion temperatures of PFA from New Zealand sub-bituminous coals

The ash fusion temperatures of 20 analysed samples of pulverized fuel ash obtained from the Meremere coal-burning power station have been determined. It is shown that the fusion temperatures can be related to the acid-soluble calcium and iron oxide contents, and that it is possible to predict the softening and hemisphere temperatures of ash cubes with a precision of ca. 10 to 20 °C in either oxidizing or reducing atmospheres. Removal of the magnetic iron fraction from the PFA reduced both the softening and hemisphere temperatures by ca. 10 to 15 °C in an oxidizing atmosphere, and in a reducing atmosphere it increased the softening temperature by ca. 10 °C and the hemisphere temperature by ca. 30 °C.

A study of production and growth of sulfate particles in plumes from a coal-fired power plant

A number of airborne plume sampling experiments designed to examine the importance of sulfate particle-generating chemical reactions within coal-burning power station plumes are described. The flights were conducted downwind of the Keystone Generating Station in western Pennsylvania, with The Penn State University research aircraft, an Aerocommander 680E. On-board aerosol sampling instrumentation included a condensation nucleus counter, an optical particle counter and an electrical aerosol analyzer. A casella cascade impactor containing electron microscope copper grids coated with carbon film was used to collect particles at varying distances from the stacks. These samples were analyzed for sulfate content and particle size distribution. Measurements of SO 2 were made with a rapid-response pulsed fluorescent analyzer. Atmospheric pressure, temperature, dewpoint, winds and aircraft position were also monitored. For each flight, a vertical spiral aircraft sounding was made upwind of the power station to determine atmospheric stability and background aerosol particle and SO 2 concentrations. Downwind, the flight pattern consisted of a series of cross wind and longitudinal plume penetrations out to distances at which SO 2 reached background levels. During the case in which cooling tower plume and stack plume merger occurred, sampling continued out to regions where the liquid plume had dissipated. It was found that when relative humidity was low, stability near-neutral and solar radiation intense, the production of new Aitken particles was the primary mechanism of SO 2 oxidation. In the case of merger between the stack plume and the cooling tower plume, the formation of sulfate on pre-existing particles predominated over the formation of new particles. During cases with intermediate meteorological conditions both processes were of equal importance.