Coal Power Stations Research Articles

Distribution of Trace Elements during Combustion of Brown Coal in Power Stations investigated by Instrumental Neutron Activation Analysis

A number of trace elements are determined by instrumental neutron activation analysis in clay, coal and ashes and normalized to the Sc content. The normalized concentrations of Na, Rb, Cs, REE, Hf, Ta, Th and U are constant in coal and the different ash fractions indicating the binding at the clay minerals. In the finer ash particles a small enhancement of Fe, Co, Cu, Ga, Ba and W and a more drastical concentration enhancement of As, Br and Sb was observed and explained by different forms of migration. Eine Anzahl von Spurcnclementen wurden mittels instrumenteller Neutronenaktivierungsanalyse in Tonen, Braunkohlen und Aschefraklionen bestimmt und auf die Sc-Konzentrationen normiert. Die normierten Gchalte an Na, Rb, Cs, SEE, Hf, Ta, Th und U blieben in der Kohle und den verschiedenen Aschefraktionen konstant, was auf die Bindung dieser Elemente an die Tonminerale hinweist. In den feineren Aschefraktionen wurde eine geringe Erhöhung an Fe, Co, Cu, Ga, Ba und W und ein drastischer Konzenlrationsanstieg bei As, Br und Sb beobachtet und mit anderen Transportformen erklärt.

Feasibility of Iceland/United Kingdom HVDC submarine cable link

The authors address: market considerations, including forecasts for the development of electricity supply in the United Kingdom with cost of electricity from new plant; investments for the development of hydro resources in Iceland, supply of submarine cables, overhead transmission lines, and rectifier/inverter plant; marine environment, installation of cables, and cable repair; rectifier/inverter station equipment; high-voltage direct-current (HVDC) overhead transmission lines; and overall availability of the link. It is shown that: there should be no major difficulties in the manufacture and laying of submarine cables of the length and type necessary for the link; the availability of the connection should be at least equal to that of a new coal or nuclear plant; and the cost of energy delivered would be very competitive with that from new coal or nuclear power stations. >

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.

フライアッシュを原料とするく溶性けい酸カリ肥料の製造

As an effective utilization of coal ash generated from coal power station, production of citrate-soluble potassium silicate fertilizer were studied experi-mentally using fluidized bed.The fly ash discharged from electric dust-collector was the main raw material for the fertilizer, and it was mixed with caustic potash and potassium carbonate and others. Pulverized coal of approximately 10wt% was added to the raw materials, mixed up sufficiently and granulated -2mm in diameter with a pelletizer. The granular raw material were fed into a fluidized bed reactor and baked up to the fertilizer at 850°C to 1100°C. In this process, the heat of combustion of added coal was supplied as a heat required to baking process. Mean residence time of particles in the reac-tor, which effects to the quality of the fertilizer, was controlled by coal content in the raw materials.Based on the present baking process, a commercial plant of production of the fertilizer was constructed and has been operated in Japan.

Processes for the combined production of hydrogen and other chemical products: Desulphurization processes producing hydrogen

The various possibilities of producing H 2 in desulphurization processes are investigated. An assessment has been made of the S contained in various raw materials for industrial processes used in the F.R.G. This assessment shows that it is attractive to develop this type of desulphurization process. Large amounts of H 2 could be produced while converting environmentally and technically undesirable wastes into useful products or acceptable wastes and conserving hydrocarbon feedstocks. The H 2 equivalents which could theoretically be produced depend on the form in which S enters and leaves the process. Assuming that all the S in the F.R.G. would be available as H 2S and H 2SO 4 or that a sulphate would be produced, this would about equal the total H 2 demand of Western Germany. H 2-producing desulphurization processes are at present most attractive in petroleum refineries. They could be more attractive for coal or oil-fired power stations if appropriate processes for the reduction of NO and SO 2 with H 2 were developed. They also offer the possibility of reducing the waste volume.

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.

Mix design and properties of concrete made from PFA coarse aggregates and sand

Pulverised fuel ash (PFA) is the principal waste product obtained from coal burning power stations in the generation of electricity. Vast volumes of such PFA anticipated further in the next two decades would create serious disposal and environmental problems in many countries. One effective method of utilising these large volumes of PFA is to manufacture aggregates from them for plain and structural concrete. The paper presents extensive test data on the mix design, strength and elasticity properties of concrete made from PFA coarse aggregates and sand and having 28 day strengths of 20 to 60 N/mm 2. A mix design chart is given together with equations related to strength and elastic modulus. Stress-strain curves for such concrete for structural applications are also reported.

Long March II

Introduction In October, 1934, Mao Tse-Tung led his armies on a 6,000-mile march across China. This gruelling one-year trek known as "The Long March" crossed 18mountain ranges and 24 rivers and was one of the heroic events in China'smodern history that culminated in her liberation on October 1, 1949. Another trek is now taking place in China - Long March II - the arduousjourney to industrial growth and economic prosperity. And, leadinginternational corporations and businessmen are joining in on Long March II. China is surviving the current world recession well. Where other countriesare foundering under enormous debt loads, China remains virtually debt free.Intensely competitive foreign suppliers of goods and services are beating apath to her doors thus ensuring a huge storehouse of products at bargainprices. "China is a tough market" say both experienced and novice China watchers andtraders. And yet, the hotels of Beijing (Peking) are crammed with businessmen, year round, all hoping to close deals with this stirring giant. Think of onebillion people in an area slightly smaller than Canada, all eager for theimplementation of policies to improve their standard of living. The growingawareness and demands of one-quarter of the world's population for food, shelter and consumer goods is staggering. Directly related to the desire for an improved standard of living is thedemand for energy and China's ability to develop her energy resources in stepwith this growing demand. Over the next 20 years, a World Bank study estimates China will spend $420 to $480 billion to develop its energy infrastructureincluding offshore petroleum exploration and production, onshore enhancedrecovery, oil and gas pipelines, coal mining facilities and hydro-electric andnuclear power stations.

High capacity magnetic separator for volatile dust

The high percentage of ferromagnetic particles/γ - Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> / in chimney dust of coal power stations and a significant industrial demand for these materials suggests the possibility of extracting them on a large scale. Currently applied magnetic separators are too small for the requirements. A magnetic separator is presented which assures high capacity of dust flow and good quality of a separated ferromagnetic concentrate. The structure of this new magnetic separator and test results are described.

Radiation technology for environmental conservation

The use of radiation technology for environmental conservation is becoming increasingly important. Commercial plants for the radiation treatment of sewage sludge to reduce pathogenic micro-organisms have been operating in the Federal Republic of Germany for the past ten years and their technical and economical feasibility has been demonstrated. Irradiation of dried sludge has been developed at the Sandia National Laboratory (USA) using Cs-137, and the construction of a commercial plant is planned in Albuquerque. At the Japan Atomic Energy Research Institute (JAERI), efforts are under way to increase the rate of composting of sludge by radiation. Regarding waste water treatment, a significant synergistic effect of radiation and ozone was found in the reduction of TOC. The construction of a gamma irradiation plant is in the planning stage in Canada, for the disinfection of virus-contaminated waste effluents from the Canadian Animal Disease Research Institute. The treatment of exhaust gases by electron beam has been studied in Japan using a large pilot plant which demonstrated that 90% of SO 2 and 80% of NO x can be removed from the flue gas of iron ore sintering furnaces. The US Department of Energy is assisting in projects for the further development of this technology for combined removal of SO 2 and NO x in flue gas from coal burning power stations.

Operational experience with fossil-fired generating plant under automatic load control

Automatic load following by fossil-fired generating units requires the control of the flow of air and fuel to the boiler, and of the steam flow to the turbine. Prototype load controllers designed to achieve this have been installed at coal and oil-fired power stations within the CEGB. The principle behind their design is that boiler-stored energy is made available only for system frequency regulation. This policy helps to maximise the regulation capability available to the grid system while minimising the cyclic damage inflicted on the plant. Test results and operating experience show that both coal and oil-fired units equipped with such load controllers respond successfully to both loading and frequency regulation demands. Evidence of improved coal-fired combustion efficiency has also been obtained.

Nuclear and the energy freedom of the West

The author in expressing his opinion about the development of nuclear power says that the basic reason for anti-nuclear campaigning is ignorance. He finds that the concern of man for preservation of his environment is misdirected. The development of nuclear technology has proceeded with much greater attention on the problems of safety techniques and preservation of the environment than the development of such branches of technology as metallurgy, coke chemistry, mining, chemical industry, coal power stations, modern transportation, chemicalization of agriculture, etc. Therefore, the present situation in nuclear power is relatively good from the point of view of safety and possible effects on the environment. It is difficult to explain to a non-specialist (though it is actually true) that the nuclear reactor of a nuclear power station is nothing like an atomic bomb that the power station burning coal or oil offers much greater danger and harm to the environment as well as a biological threat to people than does a nuclear station or breeder reactor of the same capacity rating. The author also sees nuclear energy as the only economically feasible method available in the next few decades as an alternative to oil. This applies to countries--developed and developing--whomore » do not have oil. What is involved is not just comfort, or preservation of quality of life, but the much more fundamental problem of economic and political independence, Mr. Sakharov concludes. (MCW)« less

Natural radionuclides in industrial and rural soils

Radium-226, lead-210, uranium and thorium are dispersed in the environment by fly ash emitted by coal fuelled power stations. Concentrations of these nuclides have been determined in fly ash from three power stations and in soils collected in six industrial and twenty rural regions. In industrial areas the concentrations of natural radionuclides, in a 5 cm thick surface soil layer, were found to be higher than in lower layers. With the exception of lead-210 this effect was not observed in rural soils, which contained less of radium-226, uranium and thorium. It was found that the type of coal, or combustion technology, influences the amount of radium-226 dispersed in the environment which is accessible to plants.

The Dinorwic pumped-storage scheme

The CEGB has a statutory obligation to provide electricity within ±0.5 Hz of the nominal 50.0 Hz frequency and within ±6% of the declared voltage. The objectives are met by operating 137 coal, oil, gas, nuclear and hydro power stations in a highly integrated power system. In such systems, pumped-storage plants can assist in meeting the objectives in a number of ways

Coal in Long-Range Energy Pattern of United States: ABSTRACT

Coal, in 1900, supplied nearly 90% of United States energy demand, but only 23% in 1965. Oil and gas, which together contributed 8% in 1900, accounted for 73% in 1965. Nuclear energy is expected to contribute 5% of demand in 1980 but fossil fuel production will continue to grow, with coal consumption increasing from 470 million tons in 1965 to 750 million tons in 1980; natural gas increasing from 16 Tcf. in 1965 to 25 Tcf. in 1980; and oil increasing from 4 billion bbls. in 1965 to 6.7 billion bbls. in 1980. Despite the inroads of nuclear fuels, electricity generation will account almost entirely for the tonnage increase in coal consumption during this period. To secure this increase, research and development activities are being intensified to lower the cost of the delivered coal and to effect improvements in the combustion of coal in conventional thermal power stations. Ash deposits and corrosion are under intensive investigation, as are economical means for abating the emissions of sulfur and nitrogen compounds and fly ash that contribute to atmospheric pollution. Studies in progress on the location of power plants over the coal measures include means of economizing on water requirements and on long-distance power transmission. Coal-fired gas turbines and magneto-hydrodynamics are acti ely being investigated. Methods to improve the production of coke, char, and chemicals from coal carbonization are studied continuously. The increasing consumption of oil and natural gas is expected to create pressure on domestic supply by 1980. The gap between supply and demand in the period beyond 1980 may be filled in part by substitution of electricity for gas and by synthetic oil and pipeline gas derived from coal or oil shale. Research activities End_Page 2031------------------------------ in these fields have been in progress for more than 2 decades, and, with the aid of Federal funds, now are expanding at a rate designed to insure adequate supplies of oil and gas at low cost in the future. Synthetic oil processes under development include a variety of coal-hydrogenation and gas-synthesis processes. To supplement natural gas, several processes are being studied for pipeline gas production by means of hydrogasification, or by partial or total gasification of the coal and converting the synthesis gas to high-BTU pipeline gas. In support of these and many and other coal-utilization development activities, fundamental studies are conducted in many universities, research institutes, and private and government laboratories. End_of_Article - Last_Page 2032------------

Capillary Water Absorption of Blended Portland Cement Mortar

The tests of capillary water absorption and of the strength of the mortar of portland cement blended with (1) 20-70% of fly ash, and with (2) 20-50% of siliceous earth mined, respectively, from Yorii and Beppu districts, were carried out.The fly ash from a coal power station was used partly as it was, and partly after grinding in laboratory.The siliceous earths, sun dried, or dried at 110°C, were ground to a finer size than portland cement, and a part of which was calcined at 750°-840°C.All these materials, after passing through the respective pretreatments were subjected to the tests.The blending with fly ash gave a by far larger absorption than pure portland cement, partly because of the same mix-proportion by volume used for preparing mortar regardless of the substitution ratio, which made W/C by weight of blended cements larger.The siliceous earths, both Yorii and Beppu, showed by far smaller absorption than pure cement at the age of 4 and 5 weeks. The effect of calcination on the reduction of the absorption of blended cement was obvious in Yorii brand, while it is not clear in Beppu brand. When the blending with siliceous earth decreased the absorption of cement the ratio of absorption to evaporation (A/E) decreased with decreasing absorption, indicating that the smaller absorption does not run parallel with smaller evaporation. In other words it may be concluded that a blended portland cement will tend to dry when exposed to air. It may be said that the cements blended with Yorii or Beppu earth are suitable to use in wet surroundings.Bending strength of Yorii-earth mortar after 3 weeks was nearly the same with, or larger than that of pure cement, but its compressive strength showed less development.Calcination of Yorii earth made the strength larger. The strength of the simply dried Beppu earth at the age of 5 or 6 weeks was larger than that of pure cement. Calcination showed no good effect on the strength in the case of blending with Beppu earth.

Power station coal supplies

Power station coal supplies