A theoretical model of exergy balance, based on availability transfer and flow availability, in the process of pulverized coal combustion in a tubular aircoal combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions. The velocity, temperature, and concentration fields required for the evaluation ...
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Since substantial heat losses occur due to the optical access, selfsustained pulverized coal combustion is not possible and, in addition to the 20 kW thermal power from coal, 20 kW thermal power from an assisted methane gas flame is required for stable operation. ... Description of the char conversion process in coal combustion based on ...
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Combustion stability. Pulverized coal combustion is a twostage process. At the burner front volatile components in the coal are burned, generating the heat required to ignite incoming coal. If coal volatile matter content is too low then insufficient heat is generated at the burner front and flame stability is compromised.
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The pulverized coal combustion process can be divided into devolatilization and char combustion and gasphase combustion process. The devolatilization process is described by tworeaction rates model (Kobayashi model) with calculated yield values of light and heavy volatiles Y 1 and 2 ...
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To reduce the CO2 emission of coal power generation, pulverized coalammonia combustion has been studied. In this research, to investigate the influence of ammonia coal cocombustion on coal ...
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Experimental Facility. As depicted in Figure Figure1 1, the studied boiler was a MPa/541 °C/540 °C subcritical cornertangentially pulverized coalfired boiler, with a singlefurnace chamber of 61,000 mm in height and a crosssectional area of 14,022 × 13,640 the primary combustion zone, five coal burners and seven secondary air nozzles are installed alternately on the four ...
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Pulverized Coal Combustion in Supercritical Steam Cycle. Pulverized coalfired supercritical steam boilers ( 250 atm, 2×853 K), have been in use since the 1930s, but improvements in materials and increasing demand for higher efficiency are making this system the choice of new coalfired utility plant worldwide.
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Fig. 3 shows the basic concept of the pulverized coal combustion process. When the pulverized coal particle is heated up, moisture evaporates from the particle at the temperature range of boiling point of water. The volatile matter, which includes various gas species and tar, evolves from the particle by the devolatilization process: the ...
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The paper presents experimental and numerical investigation of pulverized coal combustion process analysis and optimization. The research was conducted on the frontfired pulverized coal boiler with dedicated lowNOx furnace installation. In order to find optimal boiler operating conditions the acoustic gas temperature measurement system and mass flow rate of pulverized coal measurement system ...
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Coal combustion technology has been further developed since the late nineteenth century. The coal fixedbed stoker system was invented in 1822; the firing of pulverized coal occurred in the brickkiln in 1831, and fluidizedbeds were invented in 1931. Nowadays, direct coal combustion is extensively utilized for industrial and domestic
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Characteristics of pulverized coals have significant influence on the spontaneous combustion and explosion processes. This paper presents an experimental and theoretical framework on physicochemical characteristics of coal and their interrelations from spontaneous combustion and explosion perspectives. The chemical properties, morphology, bulk density, particle size, and specific surface area ...
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The main experienced process of pulverized coal during combustion in the CFB are: drying and heating of coal, precipitation and combustion of volatiles, and combustion of coke [4]. Among them, the coke generation and conversion behavior have a very important impact on the final NOx emissions and combustion performance of pulverized coal.
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Pulverized coal combustion is a complicated process and its simulation requires a number of models for turbulence, combustion and radiative heat transfer. Each of these requires a considerable simplification of the underlying phenomena and, to a large extent, there is some standardization of the CFD modelling of pulverized coal combustion ...
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Sintering accounts for about 50% of the total NOx emissions of the iron and steel industry. NOx emissions from the sintering process can be simulated using the emissions from coke combustion. However, the generation and emission law for NOx burning in the sintering process of pulverized coal is still not clear. The formation characteristics of NOx during coal combustion catalyzed by iron ore ...
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Fig. 8 gives the geometrical configuration of the burner and pulverizedcoal concentrator for calculated swirling combustion. It has three inlets: primaryair inlet, swirling secondaryair inlet and nonswirling secondaryair inlet. When a pulverizedcoal concentrator designed by authors is installed in the primaryair tube, the burner is called a bias coal swirl burner (Case 1).
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Therefore, the surface of pulverized coal is oxidized directly by contact with oxygen, and only a small amount of volatiles are oxidized inside or on the surface of particles. The combustion process can be divided into two stages: a preheating process and a coal char burning process, which is dominated by a heterogeneous oxidation reaction.
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Other articles where pulverizedcoal combustion is discussed: coal utilization: Pulverized coal: Pulverizedcoal combustion is widely used in large power stations because it offers flexible control. In this method, coal is finely ground so that 70 to 80 percent by weight passes through a 200mesh screen. The powder is burned in a combustion chamber by.
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This article presents an experimental study on the effects of airstaged strategy and NH3 cofiring on NOx emissions and combustion characteristics of pulverized coal in a drop tube furnace. The results show that NH3 cofiring can significantly reduce NOx emissions and improve combustion efficiency under different airstaged conditions. The article also analyzes the mechanisms of NOx formation ...
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Coalfired industrial boilers should operate across a wide range of loads and with a higher reduction of pollutant emission in China. In order to achieve these tasks, a physical model including two swirling burners on the front wall and boiler furnace was established for a 35 t/h pulverized coalfired boiler. Based on Computational Fluid Dynamics (CFD) theory and the commercial software ANSYS ...
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The TGDTGDSC curves of the pulverized coal combustion process of two types of MDS with different ratios are demonstrated in Figure 7. According to the peak shape of the DTG and DSC curves, the combustion process of pulverized coal can be divided into two stages: (1) The volatile escaping and homogeneous combustion stage (260410 °C); the ...
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In the pulverized coal injection (PCI) process of a blast furnace (BF), intensifying the combustion of pulverized coal in the raceway and tuyere is the key to increasing the injection ratio. 3,4 In addition to widely used technologies that cooperate with PCI, such as oxygen enrichment and high temperature of hot blast air, 5,6 the catalytic ...
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The CFD analysis was conducted using ANSYS Fluent, and the pulverized coalcombustion process was modeled using the EulerLagrangian approach. In the model, the continuous gas phase is treated as a continuum by solving NavierStokes equations in the Eulerian frame, and the dispersed phase is solved by tracking a large number of ...
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Section snippets Numerical simulation. For this study, we considered a model burner (Fig. 1) one eighth of the size of the prototype designed for a 600 MW pulverizedcoal utility Fig. 1, L p is the primary air cone length, L i is the inner secondary air cone length, and L o is the outer secondary air cone length of the model burner. The configurations of the computational domain and ...
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Pulverized coal injection technique has been widely used as a means of reducing coke consumption during ironmaking process. Owing to the increasing shortage of fossil fuels, other substitutes such as biomass, plastic, and waste tires have been studied in recent years. Coke breeze as one of the byproducts of coking industries has been investigated as a substitute for partial pulverized coals ...
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The pulverized coal combustion process follows a sequence of phenomena involving drying, devolatilization, homogeneous and heterogeneous reactions and char burnout. Modeling of turbulence. The standard kε model provides reasonable results in an acceptable computational time compared to other turbulence models (Wang et al. 2014).
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In the pulverized coal injection (PCI) process of a blast furnace (BF), intensifying the combustion of pulverized coal in the raceway and tuyere is the key to increasing the injection,4 In addition to widely used technologies that cooperate with PCI, such as oxygen enrichment and high temperature of
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Pulverized coal injection (PCI) is a special process used in blast furnaces in which pulverized coal is preheated. However, there are few studies on the application of this technology in industry. In this paper, the combustion of pulverized coal in the tuyere of a blast furnace with different preheating temperatures and PCI rates is observed by a digital imaging detection system.
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The paper presents results of numerical modeling of pulverized coal combustion process in the front wall coalfired boiler. The developed numerical model of the coal combustion process included particle heating, devolatilization, char combustion, as well as turbulent flow and radiative heat transfer.
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The progresses on both numerical methods and coal combustion models are highlighted. The stateoftheart applications of these highfidelity simulations are also reviewed, including the investigation of combustion characteristics of pulverized coals, the development of advanced coal combustion models, and the development of clean coal ...
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The production process of direct reduced iron from titanomagnetite by coal reduction in air in rotary kiln is a key step in the extraction of titanium and iron. This process is conducive to alleviating the stocking problem of a large amount of Tibearing blast furnace slag. The relationships between particle movement and pulverized coal injection combustion in rotary kiln were studied by the ...
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Other models for devolatilization and combustion of solid and liquid fuels, considering harmful emissions, such as NOx, are evaluated. Xu et al. employed the CFD code to analyze a coal combustion process in a pulverized coal utility boiler of 350 MWe with 24 swirl burners installed at the furnace front wall. Five distinct cases with 100, 95, 85 ...
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These benefits make it a highly promising solution to meet the demand for flexible peak shaving. The pulverized coal in the selfpreheating device (SPD) undergoes a gasification reaction and exothermic combustion process [27,28]. The gassolid fuel mixture is subsequently fed into the combustion chamber for suspension combustion [29,30].
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Pulverized coal combustion process occurs in a highly turbulent environment. Hence, the combustion and mixing of turbulent gaseous species plays a significant role in the combustion of coal particles. The alternatives for modeling the homogeneous gas phase combustion are shown in Fig. 3. The choice of the model depends on the which of the two ...
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The process of heating coal in this manner is referred to as carbonization or coke making. Hightemperature carbonization, with which this section is concerned, is practiced to produce a coke having the requisite properties for metallurgical use, as in blast furnaces or foundry cupolas. ... Pulverized coal. Pulverizedcoal combustion is widely ...
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Large quantities of lowvolatile coal are utilized in power plants throughout China. With increasingly stringent environmental regulations, it is important to develop and deploy lowNO x combustion technologies for pulverized coal boilers burning lowvolatile coal. The objective of this study was to investigate a novel decoupling combustion system for lowvolatile coal via experiments and ...
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A material supplier from Belgium would like to produce limestone powder for his custome...
India is rich in various mineral resources and it is an important mineral processing market
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